Words for three and related things in Celtic languages:
| Proto-Celtic | *trīs = three *tritiyos = third (in a sequence) *trisano- = third (fraction) |
|---|---|
| Celtiberian | Tiriś = three |
| Gaulish | treis = three (m) tiđres = three (f) |
| Lusitanian | *trīs = three |
| Old Irish (Goídelc) | tri, trí [tʲrʲiː] = three tress = third (in a sequence) trían = third (fraction) tríar = three (people) tréide = three things trédenus = three days tréimse = three months |
| Middle Irish (Gaoidhealg) | trí = three tress = third (in a sequence), one of three trímad = third (in a sequence) trían = third (fraction) tríar = three persons, trio, three things tréimse = three months, a quarter (of a year) |
| Irish (Gaeilge) | trí [tʲɾʲiː] = three tríú [tʲɾʲiːuː] = third (in a sequence), third part triúr [tʲɾʲuːɾˠ] = three (people) triantán = triangle triantánacht = trigonometry triantánaigh = to triangulate tríoiseach = three-dimensional |
| Scottish Gaelic (Gàidhlig) | trì [triː] = three treas [tres] (3ˢ) third (3ʳᵈ) treasamh (3ᵐʰ) third (3ʳᵈ) triùir [truːrʲ] = three (people) trì-fillte = triple, threefold, three-ply trian [triən] = third (part) triantan [triəndan] = triangle iantanachd [iantanachd] = trigonometry |
| Manx (Gaelg) | tree [t̪riː] = three troor = three (people), threesome, triad, Trinity, trio, trinity treeoo, trass = third trooane, troorane = triangle |
| Proto-Brythonic | *tri [triː] = three (m) *teir = three (f) *trɨdɨð [trɨˈdɨːð] = third (m) *trɨdeð = third (f) |
| Old Welsh | *tri [triː] = three (m) *teir = three (f) tritid = third (in a sequence) trean = third (fraction) |
| Middle Welsh (Kymraec) | tri = three (m) teir, tair = three (f) trited, trydet, trydyd = third teir coglaỼc, trichonglaỼc, trichongloc = triangular, three-cornered trydeblyc, tridyblic = three times, threefold, triple |
| Welsh (Cymraeg) | tri [triː] = three (m), tair [tai̯r] = three (f) triawd = trio, threesome, triology, triple trichorn = three-horned, three-cornered, tricorn hat tric(h)onglog = triangular, three-cornered tri deg = thirty tridyblyg = three times, threefold, triple, triplicate trionglyn = triangle trydydd (3ydd) = third (m) trydedd (3edd) = third (f) teirgwaith = three times, thrice, on three occasions |
| Middle Cornish (Cernewec) | tri, trei = three (m) teir, teyr = three (f) triddydh = the space of three days tridzha = third trihans = three hundred trindas, trinsys = Trinity triugans = three score, sixty trivorh = three-pronged |
| Cornish (Kernewek) | tri, trei = three (m) trei = three (f) tredhek, terdhek = thirteen tressa, tryja = third triasen = triplet trihorn = triangle tryflek = threefold, triple teyrgweyth = three times |
| Old Breton | tri = three |
| Middle Breton (Brezonec) | tri, try = three (m) teir, teyr = three (m) tri-c’hard = three quarters tri-ugent = sixty tri-chant = three hundred triad = trio, group of three tric’hogn, tricoign, tric’horn = triangle |
| Breton (Brezhoneg) | tri = three (m) teir [ˈte.iʁ] = three (f) trived (m) teirved (f) = third trizek = thirteen tri-ugent = sixty trifarzh = three quarters tric’horn, tric’hogn = triangle |
Etymology: from Proto-Indo-European *tréyes (three – m) and *tisres (three – f) [source].
English words from the same roots include tertiary, three, thrice, three, triad, tripod, triple and triplex [source].
Sources: Wiktionary, Am Faclair Beag, Online Manx Dictionary, Teanglann.ie, eDIL – Electronic Dictionary of the Irish Language, In Dúil Bélrai English – Old Irish glossary, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Gerlyvyr Cernewec, Dictionaire Favereau, TermOfis, Le dictionnaire diachronique du breton, Geriafurch, English – ProtoCeltic WordList (PDF), Etymological Dictionary Of Proto Celtic
“English words from the same roots include tertiary, three, thrice, three, triad, tripod, triple and triplex”.
I see you noted “three” twice. At least it’s not thrice! Maybe that song idea about “twice” needs a second (or third!) look.
BTW, I seem to recall in my high school days (a tad and a smidgen over 50 years ago) that I read a book called “One, Two, Three, Infinity”. In its introduction, there was mention of some tribe that only had number words for one, two and three. Any amount over three was basically “many”. Are there still languages that are thusly so numerically challenged? I would be hesitant to label people with such a limited language as “primitive” but the word comes to mind.
Ever hear of such a thing?
There are some languages that have only a few numbers words, including Pitjantjatjara – https://www.omniglot.com/language/numbers/pitjantjatjara.htm