Words for talkative, to speak, to sing and related things in Celtic languages.

Words marked with a * are reconstructions.

Proto-Celtic	*ɸlabros = talkative *amɸlabros = dumb, mute
Old Irish (Goídelc)	labar = talkative, boastful labraithir = to talk, speak amlabar = dumb, mute
Middle Irish (Gaoidhealg)	labar = talkative, arrogant, boastful labraithir = to talk, speak labarthach = talkative, noisy labra = gift of speech, talkativeness, utterance, sound, speaking labraithir = to speak, talk, utter, say amlabar = dumb, mute
Irish (Gaeilge)	labhair = to speak, hail labhairt = speaking, speech, utterance, voice, call labharthacch = talkative, vociferous, noisy labharthacht = talkativeness labhra = speech, utterance amhlabhra = inarticulateness, bad delivery amhlabhrach = crude of speech, inarticulate
Scottish Gaelic (Gàidhlig)	labhair [l̪ˠau.ɪrʲ] = to speak, say, talk, speak!, utter! labhar = speaking loudly, loquacious, boastful labhairt = speaking, uttering, utterance labhairteach = loquacious, oral labhairte = said, spoken amhlabhair = mute, dumb, speechless (obsolete) co-labhairt = conference, symposium neach-labhairt = speaker, spokesperson ro-labhairt = prologue
Manx (Gaelg)	loayr = to speak, extemporise loayreyder = mouthpiece, speaker, talker loayrt = to speak, talk, utter, express loayrit = oral, spoken amloayrtagh = dumb, mute
Proto-Brythonic	*laβar [laβaːr] = prone to talking, eloquent *aβ̃laβar = dumb, mute
Middle Welsh (Kymraec)	llawar, llavar, llauar = loud, clear, vociferous lleueir, llauarei, llafaraf = to speak, say, tell aflauar = mute, dumb, speechless, silent
Welsh (Cymraeg)	llafar [ˈɬa(ː)var] = loud, clear, vociferous, resounding, resonant, sonorous; pertaining to the voice, vocal (of music, in contrast with instrumental); talkative, loquacious; spoken (language), oral, verbal llafarder = talkativeness, loquaciousness llafaredig = spoken, uttered, oral, verbal, articulate llafareiddio = to make more colloquial, speak naturally llafariad = vowel llefaru = to speak, say, tell, declare lleferydd = speech, voice, expression, uttereance, pronunciation aflafar [avˈlavar] = mute, dumb, speechless, silent
Old Cornish	lauar = talkative aflauar = dumb, mute
Middle Cornish (Cernewec)	lavar = utterance, speech, voice, a saying, word, proverb lavary = to speak, say, tell, pronounce, declare avlavar, afavar = speechless, dumb, mute
Cornish (Kernewek)	lavar = expression, idiom, utterance, sentence lavaren = phrase amlavar = dumb, mute leverel, lawl = to pronounce, say, tell leveryans = pronunciation avlavar = dumb
Old Breton	labar = talkative
Middle Breton (Brezonec)	lauaret = to say, promise
Breton (Brezhoneg)	lavar [ˈlɑːvar] = to say, word, language lavaradenn – to tell lavarenn [laˈvɑːrɛn] = proposal lavaret = to say, promise lavariant = communicative lavariantiz = communication amlavar = dumb, mute

Etymology: possibly from Proto-Indo-European *pl̥b-ró-s, from *pleb- (to babble), which is also the root of words such as barbarian in English, pleurer (to cry) in French, and llorar (to cry, weep) in Spanish [Wiktionary].

Old Irish (Goídelc)	asbeir [asˈbʲerʲ] = to say, utter, mention, speak
Middle Irish (Gaoidhealg)	atbeir = to say, speak
Irish (Gaeilge)	abair [ˈabˠəɾʲ] = to say, utter, speak, express, state, allege, give opinion, suppose, assume, mean, direct, report abairt sentence, phrase abartha given to repartee
Scottish Gaelic (Gàidhlig)	abair [abɪrʲ] = to say, speak, utter, tell abairt [abər̪ˠʃdʲ] expression, phrase, collocation, saying, comment abartach [abər̪ˠʃdəx] talkative, bold. impudent
Manx (Gaelg)	abbyr = to say, state, assume abbyrt = sentence, dialect, phrase, expression, period

Etymology: from the Proto-Celtic *ess (ex-, out) and *beirid (to carry, bring, bear, give) [source].

Proto-Celtic	*kaneti = to sing *kantlom = singing *toɸareuɸokaneti = to prophesize
Old Irish (Goídelc)	canaid = to chant, praise, recite, sing, speak cainnt [kan͈ʲtʲ] = speech, talk, conversation; act of speaking
Middle Irish (Gaoidhealg)	canaid = to sing, recite, chant canamain = singing, chanting cantain = singing, reciting, chanting, uttering cainnt = speach, talk, conversation, act of speaking cainntech = talkative, loquacious
Irish (Gaeilge)	can [kan̪ˠ/kanˠ] = to chant, sing, speak, talk, call, name canadh [kan̪ˠə/ˈkanˠuː] = singing, chanting cantaire = chanter, chorister caint [kan̠ʲtʲ / kəin̠ʲtʲ] = speech, talking cainteach = talkative, chatty cainteoir = speaker, talker caintigh = to speak, address, accost
Scottish Gaelic (Gàidhlig)	can [kan] = (to) say cainnt [kãĩn̠ʲdʲ] = to speak, talk, commune cainnteach [kãĩn̠ʲdʲəx] = loquacious, talkative cainnteanas [kãĩn̠ʲdʲənəs] = speech cainntear [kãĩn̠ʲdʲər] = orator, speaker cainntearachd [kãĩn̠ʲdʲərəxg] = eloquence, rhetorical expression cainnteas [kãĩn̠ʲdʲəs] = attractive speech cànan [kaːnan] = language cànanachas = linguistics cànanaiche = linguist
Manx (Gaelg)	caaynt = spoken language, spoken word, talk caayntagh = loquacious
Proto-Brythonic	*kėnɨd [ke̝ˈnɨːd] = to sing
Old Welsh	canam = to sing
Middle Welsh (Kymraec)	kan, cân = song kanu, canu = to sing kantor, kantoryeit = singer, songster, vocalist, musician, cantor kanwr, kantoryeit = singer, vocalist ynganv = to speak, talk, say
Welsh (Cymraeg)	cân [kaːn] = song canaf, canu [ˈkanɨ̞/ˈka(ː)ni] to sing; to intone, chant, to state, say, to produce musical sounds, to play (the harp, piano, etc), to compose poetry, to celebrate in song cantor, cantores = singer, vocalist, musician, cantor canwr = singer, vocalist ynganu = to speak, talk, say, tell, declare, express, pronounce
Middle Cornish (Cernewec)	can = song canas = song cane, cana = to sing (a song), to sing as birds, to crow canor, canores = singer
Cornish (Kernewek)	kan = poem, song kana [‘kana / ‘kɒnɐ] = to sing kaner, kanores = singer kanik = ditty, jingle
Middle Breton (Brezonec)	can = song canaff = to sing caner = singer
Breton (Brezhoneg)	kan [ˈkãːn] = song kanadeg = concert, cantata kanañ [ˈkãː.nã] = to sing kanaouenn [kã.ˈnɔ.wːɛn] = song kaner [ˈkãː.nɛr] = singer

Etymology: from the Proto-Indo-European *keh₂n- (to sing) [source]. The English words accent, cant, chant, charm, enchant, hen and incantation come from the same root, as does the Breton word kentel (lesson, moral), the French word chanter (to sing), and the Spanish word cantar (to sing) [source].

Proto-Celtic	*kom-wep-s- = conversation
Welsh (Cymraeg)	comio = to talk converse ymgom = (subject of) chat or conversation ymgomiad = chat, conversatoin, talk, dispute, debate ymgomio, ymgoniaf = to chat, converse, mention, discuss, dispute, debate ymgomiol = chatty, conversational, colloquial ymgomiwr = conversationalist, talker, speaker
Middle Cornish (Cernewec)	cews, cowms, cows = speech, discourse, talk cewsel, cowsa = to speak, say, tell, relate cows = to speak, say, tell cowses = a speech, discourse
Cornish (Kernewek)	kows [kɔʊz] = to speak, talk kewsel [ˈkɛʊzɛl] = to speak, talk
Middle Breton	comps = speech, to say, tell, pronounce
Breton (Brezhoneg)	komz [ˈkɔ̃ms] = to speak, talk, express oneself komzapl = expressible komzer = speaker komzerzh = expression komzidigezh = speech komzus = expressive

Etymology: from Proto-Celtic *kom- (with) and *wepos (speech, voice), from Proto-Indo-European *wekʷ- (to speak), which is also the root of epic, vocal, voice and vowel in English [source].

Proto-Celtic	*kom-wep-s- = conversation
Old Irish (Goídelc)	comrád = conversation, dialogue, talking
Middle Irish (Gaoidhealg)	comrád. comrad = conversing, talking, dialogue, speech, utterance, saying comráidid = to converse comráitech = chatty, talkative
Irish (Gaeilge)	comhrá [ˈkoːɾˠɑː/ˈkõːɾˠɑ̃] = conversation comhráiteach = conversationalist, conversational
Scottish Gaelic (Gàidhlig)	còmhradh [kɔ̃ːrəɣ] = conversing, conversatoin, dialogue, discussion, negotiation
Manx (Gaelg)	cowag = babble, chat

Etymology: from Old Irish com- (mutual, joint, co-) and rád (speech, talk, conversation), from Proto-Celtic *kom- (with) and *rādīti, from *rādī (to talk) [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, Dictionaire Favereau, TermOfis, English – ProtoCeltic WordList (PDF), Etymological Dictionary Of Proto Celtic