Category: Proto-Brythonic

Going, Going, Gone

By Simon

Words for to go in Celtic languages.

Note: this is one of the few irregular verbs in the celtic languages, and some different parts of the conjugations come from different roots.

Proto-Celtic *tēgeti = to go, step
Old Irish (Goídelc) téít [tʲeːdʲ] = to go, process, depart leave
Irish (Gaeilge) téigh [tʲeːɟ / tʲeːj / tʲeː] = to go, move, proceed, get on, fare, make, cost
Scottish Gaelic (Gàidhlig) tèid = will go – (future form of rach)

Etymology: from the Proto-Indo-European *stéygʰeti (to be walking, to be climbing) [Source].

Old Irish (Goídelc) dul = to go, going
Irish (Gaeilge) dul [d̪ˠʊlˠ] = going, passing, departure, way, method, means, proper, natural, arrangement, style – (verb noun of téigh)
Scottish Gaelic (Gàidhlig) dol [dɔl̪ˠ] = (act of) going, (act of) proceeding
Manx (Gaelg) goll = to go, show out, disembark, going, sinking, passage, departure

Etymology: unknown

Proto-Celtic *monītor = go
Middle Irish (Gaoidhealg) muinithir = goes around
Proto-Brythonic *moned = go
Welsh (Cymraeg) mynd [mɨ̞nd / mɪnd] = to go, leave, depart, die, disappear, perish, come to an end, elapse, pass
Cornish (Kernewek) mos = to go, become
Breton (Brezhoneg) monet = to go, to become

Etymology: from the Proto-Indo-European *menH- [Source].

Words marked with a * are reconstructions.

Sources: Wiktionary, Am Faclair Beag, MacBain’s Dictionary, In Dúil Bélrai English – Old-Irish Glossary, teanglann.ie, On-Line Manx Dictionary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau

Roundness

By Simon

Words for round in Celtic languages.

Proto-Celtic *krundis = round
Old Irish (Goídelc) cruind, cruinn = round
Irish (Gaeilge) cruinn [kɾˠiːnʲ / kɾˠɪn̠ʲ] = round; gathered; exact, accurate; clear, coherent; concentrated; frugal, sparing, miserly
Scottish Gaelic (Gàidhlig) cruinn [krɯin̪ʲ] = round, circular, spherical; rotund; neat, succinct, well-formed; assembled, gathered together
Manx (Gaelg) cruinn = accurate, detailed, unambigous, round, spherical, circular, circumstantial, compact, consummate, exact, scrupulous, strict
Proto-Brythonic *krunn = round
Welsh (Cymraeg) crwn [krʊn] = round, circular, rotund, spherical, globular; cylindrical; fat, plump, fleshy; complete, entire; young, small
Cornish (Kernewek) krenn = round
Breton (Brezhoneg) krenn = medium, clean, full, round,

Etymology: unknown, possibly borrowed from a non-Indo-European language [Source].

Words marked with a * are reconstructions.

Sources: Wiktionary, , Am Faclair Beag, MacBain’s Dictionary, In Dúil Bélrai English – Old-Irish Glossary, teanglann.ie, On-Line Manx Dictionary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau

On the roundabout / Ar y cwmpasog

Wickedly Bad

By Simon

Words for bad in Celtic languages.

Proto-Celtic *drukos = bad
Old Irish (Goídelc) droch [drox] = bad
Irish (Gaeilge) droch = bad, poor, evil, ill
Scottish Gaelic (Gàidhlig) droch [drɔx] = bad, evil, wicked
Manx (Gaelg) drogh = evil, wicked, bad, abusive, unenviable, misfortune, badness
Proto-Brythonic *drug = bad
Welsh (Cymraeg) drwg [druːɡ] = bad, rotten, putrid, poor, piteous, wretched, sorry, grievous, sad; unfavourable, injurious, harmful, unpleasant, indecent, obscene, counterfeit, false, harsh, cruel, severe, ruthless
Cornish (Kernewek) drog = bad, evil, invalid, naughty, wicked, nasty
Breton (Brezhoneg) drouk [ˈdruːk] = bad, evil

Etymology: from the Proto-Indo-European *dʰrewgʰ- (to deceive) [Source].

Words marked with a * are reconstructions.

Sources: Wiktionary, , Am Faclair Beag, MacBain’s Dictionary, In Dúil Bélrai English – Old-Irish Glossary, teanglann.ie, On-Line Manx Dictionary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau

Clean & Pure

By Simon

Words for clean in Celtic languages.

Proto-Celtic *glanos = clean, clear
Old Irish (Goídelc) glan [ɡlan] = clear, pure, clear
Irish (Gaeilge) glan [ɡlˠanˠ] = clean, clear, pure, bright, well-made, distinct; complete, extact
Scottish Gaelic (Gàidhlig) glan [gl̪ˠan] = clean, pure, bright, sheer, downright, great, grand, grovy
Manx (Gaelg) glen = clean, fair, fresh-coloured, clear, pure, chaste, hygienic, sheer, emphatic, downright, peremptory, flat (refusal), cloudless, undefiled, clearcut, unclouded
Proto-Brythonic *glan [ˈɡlan] = clean, clear
Middle Welsh (Kymraec) glan = clean, clear
Welsh (Cymraeg) glân [glan] = clean, cleansed, neat; clear of sin, pure, good, virtuous, uncorrupted, undefiled, fair, honest, sincere; holy; fair of countenance, beautiful, handsome; complete, clean, utter, entire
Cornish (Kernewek) glan = clear, clean, pure
Old Breton glan = pure
Middle Breton glan = pure
Breton (Brezhoneg) glan = pure

Etymology: possibly from the Proto-Indo-European *ǵʰl̥h₃-nó-s, *ǵʰelh₃- (green, yellow) [Source].

Words marked with a * are reconstructions.

Sources: Wiktionary, , Am Faclair Beag, MacBain’s Dictionary, In Dúil Bélrai English – Old-Irish Glossary, teanglann.ie, On-Line Manx Dictionary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau

Gentle treasure

By Simon

Words for gift, treasure, benefit in Celtic languages.

Proto-Celtic *moinis = treasure, precious object
Old Irish (Goídelc) moín = gift, benefit
Irish (Gaeilge) maoin [mˠiːnʲ] = gift, benefit, property, wealth, treasure (term of endearment)
Scottish Gaelic (Gàidhlig) maoin [mɯːn̪ʲ] = asset, wealth, fund, gear, goods
Manx (Gaelg) mayn = property, good order
Proto-Brythonic *muɨn = beautiful
Old Welsh muin = worth, value
Middle Welsh (Kymraec) mwyn = worth, value
Welsh (Cymraeg) mwyn [muːɨ̯n / mʊi̯n] = tender, mild, gentle, meek, amiable, loving, kind, obliging, courteous, noble, fair, pleasant, sweet-sounding, melodious, soft, soothing
Old Cornish muin = gracile
Old Breton moin = delicate
Middle Breton moen = thin
Breton (Brezhoneg) moan [ˈmwãːn] = thin, slender

Etymology: from the Proto-Indo-European moynis [Source].

Words marked with a * are reconstructions.

Sources: Wiktionary, , Am Faclair Beag, MacBain’s Dictionary, In Dúil Bélrai English – Old-Irish Glossary, teanglann.ie, On-Line Manx Dictionary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau

Treasure 013-1

Animals

By Simon

Words for animals in Celtic languages.

Proto-Celtic *mīlom = animal
Old Irish (Goídelc) míl [mʲiːl] = animal, louse
Irish (Gaeilge) míol [mʲiːlˠ, mʲiːl] = animal, creature, insect, louse
Scottish Gaelic (Gàidhlig) mial [miəl̪ˠ] = louse, tick, animal (archaic)
Manx (Gaelg) meeyl [miːl] = insect, louse, gnat
Proto-Brythonic *mil [ˈmiːl] = animal
Middle Welsh (Kymraec) *mil = animal
Welsh (Cymraeg) mil [miːl] = animal, beast, creature
Cornish (Kernewek) mil = animal
Middle Breton mil = animal
Breton (Brezhoneg) mil [ˈmiːl] = animal

Etymology: from the Proto-Indo-European *(s)meh₁l- (small animal) [source].

Old Irish (Goídelc) ainmide = living creature, animal, beast, animate
Irish (Gaeilge) ainmhí [anʲəvʲiː]= animal, brute, monster
Scottish Gaelic (Gàidhlig) ainmhidh [ɛnɛvɪ] = animal, beast of burden, heifer

Etymology: from the Old Irish ainim(m) (soul, life), from the Latin anima (soul, spirt, life; breath), or from the Proto-Celtic *anaman (soul, spirit), from Proto-Indo-European *h₂enh₁mos, from *h₂enh₁- (breathe) [source].

Middle Welsh (Kymraec) anyueyl, anieuil = animal, beast, creature
Welsh (Cymraeg) anifail [aˈnɪvai̯l / aˈniːvai̯l] = animal, beast, creature
Cornish (Kernewek) eneval = animal
Breton (Brezhoneg) aneval = animal

Etymology: from the Latin animal (animal, living creature), from animālis (animate, living), from anima (soul, spirt, life; breath) [source].

Proto-Celtic *betrixs = (?)
Old Irish (Goídelc) bethach = beast, brute, animal
bethadach = animal
Irish (Gaeilge) beithíoch [bʲɛˈhiəx / ˈbʲɛhiəx / ˈbʲɛhiə(h)] = beast, (large) animal, brute; (large) specimen of creature, bovine animal; heifer, cow, cattle, horse
Scottish Gaelic (Gàidhlig) beathach [bɛhəx] = animal, beast, head of cattle, brute
beithir [behɪrʲ] = any wild or savage thing, beast; thunderbolt; lightning; strong gust of wind; warrior, hero
Manx (Gaelg) baagh = animal, pet, beast

Etymology: from the Middle Irish betha (life) [source].

Words marked with a * are reconstructions.

Sources: Wiktionary, Am Faclair Beag, MacBain’s Dictionary, In Dúil Bélrai English – Old-Irish Glossary, teanglann.ie, On-Line Manx Dictionary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau

Newborough beach

Goats

By Simon

Words for goats in Celtic languages.
Oes gafr eto?

Proto-Celtic *gabros = goat
Gaulish gabrus = goat
Old Irish (Goídelc) gabor [ˈɡavor] = goat
Irish (Gaeilge) gabhar [ɡəuɾˠ] = goat; Capricorn; scad, horse-mackerel
Scottish Gaelic (Gàidhlig) gohbar [ɡo.əɾ] = goat, Capricorn
Manx (Gaelg) goayr = goat, stooge, scad
Proto-Brythonic *gaβr = goat
Middle Welsh (Kymraec) gauar = goat
Welsh (Cymraeg) gafr [ɡavr] = goat
Old Cornish gauar = goat
Cornish (Kernewek) gaver = goat
Old Breton gabr = goat
Breton (Brezhoneg) gavr = goat

Etymology: from the Proto-Indo-European *kápros (goat) [source].

Proto-Celtic *bukkos = goat
Gaulish *bukkos = male goat
Old Irish (Goídelc) boc = he-goat, billy goat
Middle Irish (Gaoidhealg) boc = he-goat, billy goat
Irish (Gaeilge) boc = buck, playboy
poc = buck (of deer or goat)
pocán = billy goat
poc gabhair = billy goat
Scottish Gaelic (Gàidhlig) boc [bɔxg] = buck (esp. of deer and goats)
boc-gobhair = billy goat
Manx (Gaelg) bock = male, he, josser, swell, buck, gelding
bock goayr = billy goat
Welsh (Cymraeg) bwch [buːχ] = buck
bwch gafr = billy goat
Cornish (Kernewek) bogh = billy goat
Breton (Brezhoneg) bo(u)c’h = billy goat

Etymology: from Proto-Indo-European *bʰuǵ- (goat, buck, ram) [source], which is also the root of the English word buck.

Irish (Gaeilge) minseach = nanny goat
Scottish Gaelic (Gàidhlig) minnseag = nanny goat
Manx (Gaelg) mannan = nanny goat

Etymology: unknown

Proto-Celtic *menno- = young of an animal, kid
Middle Irish (Gaoidhealg) menn = kid, young goat
Irish (Gaeilge) meann = kid, young goat
Scottish Gaelic (Gàidhlig) meann [mjaun̪ˠ]= kid, young goat
Manx (Gaelg) mannan = kid, young goat
Middle Welsh (Kymraec) myn, mỳn = kid, young goat
Welsh (Cymraeg) myn = kid, young goat
myn gafr = kid, young goat
Old Cornish min = kid, young goat
Middle Cornish myn = kid, young goat
Cornish (Kernewek) min = kid goats
minen = kid goat
Breton (Brezhoneg) menn = kid goat
menn-gavr = kid, young goat

Etymology: from Proto-Indo-European *men- (small) [source].

Words marked with a * are reconstructions.

Sources: Wiktionary, Am Faclair Beag, MacBain’s Dictionary, In Dúil Bélrai English – Old-Irish Glossary, teanglann.ie, On-Line Manx Dictionary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau

Sheep

By Simon

Words for sheep and related words in Celtic languages.

Sheep in Gleann Cholm Cille

Proto-Celtic *kaɸrāxs = sheep
Old Irish (Goídelc) cáera, caíra [ˈkaːi̯ra] = ox, cow
Irish (Gaeilge) caora [ˈkeːɾˠə / ˈkiːɾˠə] = sheep, ewe
Scottish Gaelic (Gàidhlig) caora [kɯːrə] = sheep, sheepish person
Manx (Gaelg) keyrrey = sheep
Middle Welsh (Kymraec) kaeriwrch = roebuck
Welsh (Cymraeg) caer = sheep (archaic)
caeriwrch / cariwrch = roebuck

Etymology: possibly from the Proto-Indo-European *kápros (goat) [source].

Proto-Celtic *damos = ox, bull, domesticated animal
*dametos = sheep
Old Irish (Goídelc) dam [daṽ] = ox, stag, hero, champion
Irish (Gaeilge) damh [d̪ˠaw] = ox, stag; strong man, champion, corpulent person
damh alla = stag
damh comhair = one of a pair of oxen, yokefellow; equal, peer
damháire = bellowing, lowing (of oxen), belling (of stag)
damhán = small ox
damhra = oxen, yoke of oxen; stags, herd of deer
Scottish Gaelic (Gàidhlig) damh [dav] = stag (antlered, up to 4 yrs old), ox, oaf, crab missing a claw
damh-féidh = hart, stag
cho dall ri damh ann an ceò = as blind as a bat in daylight (“as blind as an ox in the fog”)
Manx (Gaelg) dow = ox, hart, stag
Proto-Brythonic *daβ̃ad = sheep
Middle Welsh (Kymraec) dauat, davad = sheep
Welsh (Cymraeg) dafad [ˈdavad/ˈdaːvad] = sheep, ewe; one who is under the charge of a spiritual pastor
defaid cymorth = sheep given to a needy person to form the nucleus of a flock
dafad ddu = black sheep, prodigal son, ne’er do-well of a family
defaid Dafydd Jos = waves, billows (“David Jones’ sheep”)
mynd yn draed defaid = to go to ruin (“to become sheep’s feet”)
Old Cornish dauat = sheep
Cornish (Kernewek) davas = ewe, sheep
kig davas = mutton
Breton (Brezhoneg) dañvad [ˈdãː.vat] = sheep; overly kind, gentle person; cuckold, flock; small, fluffy clouds, foamy waves
dañvadez = ewe

Etymology: the Brythonic words come from *dametos, which comes from *damos. Both these words come from the Proto-Indo-European *demh₂- (to domesticate, tame) [source]. The English words tame, (in)domitable and danger come from the same PIE root [source].

Proto-Celtic *retio- = ram
Old Irish (Goídelc) reithe [r͈ʲeθʲe] = ram; boats used as fireships
Irish (Gaeilge) reithe = ram
Scottish Gaelic (Gàidhlig) reithe [r͈ʲe.ə] = ram, tup; Aries
Manx (Gaelg) rea = ram, tup

Etymology: unknown [source].

Middle Welsh (Kymraec) hwrd, hwrt = ram
Welsh (Cymraeg) hwrdd = ram; a stupid person; battering ram; rammer, beater; Aries
Old Cornish horþ = ram
Middle Cornish hordh = ram
Cornish (Kernewek) hordh = ram
Breton (Brezhoneg) (h)ourz = ram

Etymology: unknown.

Proto-Celtic *moltos = ram, wether (castrated ram)
Gaulish *multon = sheep
Old Irish (Goídelc) molt [mol͈t] = ram, wether
Irish (Gaeilge) molt = wether, sulky, morose person
Scottish Gaelic (Gàidhlig) molt [mul̪ˠt̪ˠ] = wether
Manx (Gaelg) mohlt = castrated sheep, wether, mutton
Middle Welsh (Kymraec) mollt = castrated ram, wether, mutton
Welsh (Cymraeg) mollt [moːɬd / mɔɬt] = castrated ram, wether, mutton
Cornish (Kernewek) mols = wether, sheep
Middle Breton mout, maout = ram
Breton (Brezhoneg) maout [ˈmɔwt] = ram, mutton; champion, trophy

Etymology: uncertain, possibly from the Proto-Indo-European *(h₂)moldus (soft, weak) [source].

The Gaulish *multon is the root of the French word mouton (sheep, mutton), via the Vulgar Latin moltō (wether), and also of the Galician word motóa (sheep), and the English word mutton [source].

Proto-Celtic *ognos = lamb
Old Irish (Goídelc) úan [uːa̯n] = lamb
Irish (Gaeilge) uan = lamb
Scottish Gaelic (Gàidhlig) uan [uən] = lamb
Manx (Gaelg) eayn = lamb
Brythonic *oɨn = lamb
Welsh (Cymraeg) oen [oːɨ̯n / ɔi̯n] = lamb
Old Cornish oin = lamb
Cornish (Kernewek) oen = lamb
Breton (Brezhoneg) oan = lamb

Etymology: from the Proto-Indo-European *h₂egʷnós (lamb) [source].

Words marked with a * are reconstructions.

Sources: Wiktionary, Am Faclair Beag, MacBain’s Dictionary, teanglann.ie, On-Line Manx Dictionary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau

Cattle

By Simon

Words for cattle, cow, bull and calf in Celtic languages.

Highland cows

Proto-Celtic *bāus = cow
Old Irish (Goídelc) bó [boː] = ox, cow
Irish (Gaeilge) bó [bˠoː] = cow
Scottish Gaelic (Gàidhlig) bò [boː] = cow
Manx (Gaelg) booa = cow
Proto-Brythonic *bʉ = cow
Middle Welsh (Kymraec) bu(w) = cow
Welsh (Cymraeg) bu, buw, buyn = cow, bullock, head of cattle
biw = cow, cattle, horned cattle
Cornish (Kernewek) bu = cow
Breton (Brezhoneg) bu = cow

Etymology: from the Proto-Indo-European *gʷṓws (cattle) [source].

Proto-Celtic *boukkā = cow
Proto-Brythonic *bʉx = cow
Middle Welsh (Kymraec) buch = cow
Welsh (Cymraeg) buwch [bɨu̯χ / bɪu̯χ] = cow
Old Cornish buch = cow
Middle Cornish bugh, biuh = cow
Cornish (Kernewek) bugh, buwgh [biʊx / bɪwh] = cow
Breton (Brezhoneg) buoc’h [ˈbɥoːχ / ˈbyːɔχ] = cow

Etymology: from the Proto-Celtic *bāus (cow), the Proto-Indo-European *gʷṓws (cattle) [source].

Proto-Celtic *tarwos = bull
Gaulish taruos = bull
Old Irish (Goídelc) tarb [tarv] = bull
Irish (Gaeilge) tarbh [ˈt̪ˠaɾˠuː / ˈt̪ˠaɾˠu] =bull
Scottish Gaelic (Gàidhlig) tarbh [tarav] = bull, Taurus
Manx (Gaelg) tarroo = bull
Proto-Brythonic *tarw = bull
Middle Welsh (Kymraec) tarw = bull
Welsh (Cymraeg) tarw [ˈtaru / ˈtaːru] = bull, uncastrated male ox, papal bull, Taurus (sign of the zodiac)
Old Cornish tarow = bull
Cornish (Kernewek) tarow = bull
Old Breton taruu = bull
Middle Breton taru = bull
Breton (Brezhoneg) tarv = bull

Etymology: from the Proto-Indo-European *táwros (wild bull, aurochs) [source].

Proto-Celtic *laygos / *lāɸigos = calf
Old Irish (Goídelc) lóeg [l͈oːi̯ɣ] = calf, favourite, darling
Irish (Gaeilge) lao [l̪ˠeː / l̪ˠiː] = (young) calf
Scottish Gaelic (Gàidhlig) laogh [l̪ˠɯːɣ] = calf, kid (of deer), fawn, term of endearment for a child
Manx (Gaelg) lheiy [ax] = calf
Middle Welsh (Kymraec) lloe, lloi = calf
Welsh (Cymraeg) llo [ɬoː] = calf, bullock, simpleton, dolt
Old Cornish loch = calf
Middle Cornish) lugh = calf
Cornish (Kernewek) leugh [løːx / leːx / lɛwh] = calf
Breton (Brezhoneg) leue [ˈlø.e] = calf

Etymology: a diminutuve of the Proto-Indo-European *leh₂p- (cattle) [source].

Irish (Gaeilge) bearach = heifer, young cow
Scottish Gaelic (Gàidhlig) biorach [birəx] = a weaned but not fully mature calf or foal (up to 2 years); anti-suckling device, sucking preventer, weaner
Welsh (Cymraeg) bustach / bustych = bullock, ox, steer (possibly related to the above words)

Etymology: from the Old Irish berach [ˈbʲerax] (pointed, sharp; having pointed ears, horned), from bir (stake, spit, point; spear, spike) & -ach (related to, having, characterised by, prone to) [source].

Proto-Brythonic *oti̯on- = bullock
Middle Welsh (Kymraec) eydyon, eidon = ox, steer, bullock
Welsh (Cymraeg) eidion = domestic male of the bovine family, ox, steer, bullock, neat
Old Cornish odion = bullock
Middle Cornish udzheon, odgan = bullock
Cornish (Kernewek) ojyon = ox
Middle Breton eugenn = bullock. ox
Breton (Brezhoneg) ejon = bullock. ox
Proto-Celtic *anderā = young woman
Gaulish anderon = heifer
Old Irish (Goídelc) ainder [ˈan͈ʲdʲər] = married woman; virgin, maiden
Middle Irish (Gaoidhealg) ander [ˈæn̠ʲəɾˠ] = girl, maiden, lass; young woman
Irish (Gaeilge) ainnir [ˈæn̠ʲəɾˠ] = girl, maiden, lass; young woman (poetic); attractive woman
Scottish Gaelic (Gàidhlig) ainnir [an̠ʲɪrʲ] = maiden, virgin; nymph; marriageable woman; young woman
Middle Welsh (Kymraec) anneir = heifer
Welsh (CymraeG) anner [ˈanɛr] = heifer
Old Cornish annoer = heifer
Cornish (Kernewek) annor = heifer
Middle Breton annoer = heifer
Breton (Brezhoneg) annoar = heifer

Etymology: possibly related to Basque andere (lady, woman) [source].

Words marked with a * are reconstructions.

Sources: Wiktionary, Am Faclair Beag, MacBain’s Dictionary, teanglann.ie, On-Line Manx Dictionary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau

Horses

By Simon

Words for horse, stallion, mare and foal in Celtic languages.

Ceffylau / Horses

Proto-Celtic *kapallos = horse
Gaulish *caballos = horse
Old Irish (Goídelc) capall [ˈkapal͈] = horse
Irish (Gaeilge) capall [ˈkapˠəl̪ˠ] = horse, mare
Scottish Gaelic (Gàidhlig) capall [kahbəl̪ˠ] = mare, colt, horse, small horse
Manx (Gaelg) cabbyl = horse
Proto-Brythonic *kappilos = horse
Middle Welsh (Kymraec) keffyl, ceffyl = horse
Welsh (Cymraeg) ceffyl [ˈkɛfɨ̞l / ˈkɛfɪl] = horse, nag, hobby
Middle Cornish cevil, kevil = horse
Breton (Brezhoneg) kefel = horse

Etymology: uncertain – related to the Late Latin caballus (horse, nag), which is thought to come from the Gaulish caballos [source].

Proto-Celtic *markos = horse
Galatian *μάρκαν (márkan) = horse
Gaulish *markos = horse
Old Irish (Goídelc) marc [mark] = horse
Irish (Gaeilge) marc [mˠaɾˠk] = horse (literary / archaic)
Scottish Gaelic (Gàidhlig) marc [marxk] = charger (warhorse – literary)
Manx (Gaelg) mark-sleih = horseman
Proto-Brythonic *marx = horse
Middle Welsh (Kymraec) march = horse
Welsh (Cymraeg) march [marχ] = horse, stallion, war-horse, steed
Old Cornish march = horse
Middle Cornish march = horse
Cornish (Kernewek) margh [ˈmaɾx] = horse
Old Breton marh = horse
Middle Breton march = horse
Breton (Brezhoneg) marc’h [ˈmaʁχ] = horse, easel

Etymology: thought to be from the Proto-Indo-European *márkos, which is also the root of the English words mare and marshal, the French word maréchal (marshal), and related words in other languages [source].

Related words

Irish (Gaeilge) marcach = horseman, rider, jockey; cavalryman, Cavalier
marcachas = horsemanship
marchaigh = to ride
marcaíocht = riding, horsemanship, ride drive lift
Scottish Gaelic (Gàidhlig) marc-shluagh = horsemen, riders, cavalry
marchach = equestrian, mounted; riding
Welsh (Cymraeg) marchaidd = pertaining to a horse, horsy, horselike, equine
marchallu = horsepower
marchasyn = jackass, male donkey
marchdy = stable
marchfeddyg = horse doctor, farrier
marchfilwr = dragoon, cavalryman, cavalier, trooper
marchog = horseman, rider, jockey, mounted warrior, knight
Cornish (Kernewek) marghek = knight, rider
margh-leska = rocking horse
marghnerth = horsepower
marghogeth = to ride (a horse)
marghti = stable
horn margh = horseshoe
Breton (Brezhoneg) marc’heg = knight
Proto-Celtic *ekʷos [ˈe.kʷos] = horse
Celtiberian ekua- = horse
Gaulish epos = horse
Primitive Irish *ᚓᚊᚐᚄ (*eqas) [exʷah] = horse
Old Irish (Goídelc) ech [ex] = horse
Irish (Gaeilge) each [ax] = horse (archaic)
Scottish Gaelic (Gàidhlig) each [ɛx] = horse
Manx (Gaelg) agh [ax] = steed, riding horse
Proto-Brythonic *eb [ɛːb] = horse
Old Welsh eb = horse
Middle Welsh (Kymraec) ep, ebawl = colt, foal
Welsh (Cymraeg) ebol [ˈɛbɔl / ˈeːbɔl] = colt, foal, sucker
cyfeb = mare in foal
Middle Cornish ebol, ebel = foal, colt
Cornish (Kernewek) ebel = horse
Old Breton eb = horse
Breton (Brezhoneg) ebeul [ˈe.bøl] = foal
keneb = mare in foal

Etymology: from the Proto-Indo-European *h₁éḱwos, which is also the root of the Latin word for horse, equus, and the English word equine [source]. The horse goddess, Epona, may be related as well.

Proto-Celtic *uɸorēdos = horse
Gaulish *werēdos = horse
Proto-Brythonic *gworuɨð = horse
Middle Welsh (Kymraec) gorwydd = steed, horse
Welsh (Cymraeg) gorwydd = steed, horse

Etymology: from the Proto-Celtic *uɸo- (under) and *rēdo- (to ride; riding, chariot), from Proto-Indo-European *(H)reydʰ- (to ride) [source].

Proto-Celtic *(φ?)lārek- = mare
Old Irish (Goídelc) láir = mare
Irish (Gaeilge) láír [l̪ˠɑːɾʲ] = mare
Scottish Gaelic (Gàidhlig) làir [l̪ˠaːrʲ] = mare
Manx (Gaelg) laair = mare

Etymology: unknown [source].

Proto-Celtic *kankstikaā = mare
Welsh (Cymraeg) caseg [ˈkasɛg] = mare
Old Cornish cassec = mare
Cornish (Kernewek) kasek = mare
Breton (Brezhoneg) kazeg = mare

Etymology: from the Proto-Indo-European *ḱanḱest-/*kankest- (horse) [source].

Old Irish (Goídelc) serrach = colt, faol
Irish (Gaeilge) searrach = colt, faol
Scottish Gaelic (Gàidhlig) searrach [ʃɛr̪ˠəx] = colt, faol, filly
Manx (Gaelg) sharragh = faol

Etymology: unknown [source].

Words marked with a * are reconstructions.

Sources: Wiktionary, Am Faclair Beag, MacBain’s Dictionary, teanglann.ie, On-Line Manx Dictionary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau