Words for one and related things in Celtic languages:
| Proto-Celtic | *oinos/*oyno- = one *oynānos = alone, personally |
|---|---|
| Old Irish (Goídelc) | oen [oːi̯n] = one oenar [ˈoːi̯nər] = one person, alone, by oneself oentu [ˈoːi̯n͈tu] = oneness, unity oínḟer [oːi̯nʲer] = one person |
| Middle Irish (Gaoidhealg) | óen = one, the same, single, only, unique oenar = a single individual, one alone, one person oentu = oneness, unity, association, fellowship, alliance |
| Irish (Gaeilge) | aon [eːn̪ˠ/iːnˠ] = one, any, same, only aonad = unit aonadach = unitary aonán = individual aonar = one, lone, person, single, solitary aonarach = single, solitary, lone aonaracht = singularity, solitude aonarán = single, solitary person aontaigh = to unite aonú = first |
| Scottish Gaelic (Gàidhlig) | aon [ɯ̃ːn] = one, same, sole, approximately, about aonachd = unity, union aonaich = to combine, coalesce, unite, intergrate aonaichte = united, integrated aonan = one item/thing/person aonar = one (person), (state of being) alone aonanag = onesie aonaranach = alone, desolate, deserted, lone, solitary aonrachd = solitude, solitariness |
| Manx (Gaelg) | un [eːn/ɯːn/uːn] = one unnane = one, identical, ace (in cards) nane = one unnaneagh = particular, singular, unanimous unnaneysee, unnaneysey = to unite unnaneysit = united |
| Proto-Brythonic | *ʉn [ʉːn] = one |
| Old Welsh | un = one ungueid = once |
| Middle Welsh (Kymraec) | un, vn [ʉn] = one, single, individual unbin, vnbenn, unbyn = dictator, monarch, tyrant, despot, chief unkyrn, vncorn, ynkorn = unicorn, one-horned unweith, vn weith, vnwaith = once |
| Welsh (Cymraeg) | un [ɨːn/iːn] = one, single, individual, only, sole, unique, special, united, combined unaf, uno = to unite, unify, coalesce, amalgamate, combine, join, connect, agree, be reconciled unaidd = united, unary unawd = solo (music/dance) unawdr, unawdydd = soloist unben = dictator, monarch, tyrant, despot, chief unbriodas = monogamy uncorn, ungorn = unicorn, one-horned, chimney-stack unwaith = once, (on) one occasion, (at) one or any time, sometime |
| Middle Cornish (Cernewec) | un = one, individual uncorn = unicorn unsel = only, alone unver = of one mind, unanimous, agreed unya = to make one, unite, join unwyth = once |
| Cornish (Kernewek) | unn, udn [ˈʏn/ˈɪᵈn] = one, only, single, sole unnik = individual, only, single, sole, unique unplek = singular unran = one-piece unsel = only unses = unit, unity untu = one-sided, unilateral unver = agreed, in agreement, unanimous unweyth = incidentally, once, only unya = to unite |
| Old Breton (Brethonoc) | un = one |
| Middle Breton (Brezonec) | un, unn, unan, vnan, en, eun, oun = one unanaat = to unify unanadur = unification unanded = uniqueness unander = singular unanelezh = unit, unity |
| Breton (Brezhoneg) | un, unan = one, someone, unit, unity unvanadur = unification unander = singular unvaniñ = to unify unanelezh = uniqueness |
Etymology: possibly from Proto-Indo-European *(h₁)óynos (one, single) [source].
English words from the same roots include one, a, an and oenology (the study of wines and winemaking) [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