Celtic Languages belong to the subfamily of the Indo-European family of languages. Geographically and historically, this subfamily is divided into a Continental group (now extinct) and an Insular group. On linguistic grounds the Insular languages fall into two groups: the Brythonic (or British), including Breton, Cornish, and Welsh; and the Goidelic (or Gaelic), including Irish, Scottish Gaelic (or Erse), and Manx. Until the 5th century, Continental Celtic languages, among them, Gaulish, were spoken throughout western Europe, but little information survives about them. Only the Brythonic and Goidelic groups survive, limited to the British Isles, Brittany, and some North and South American communities.
The characteristic of Celtic languages that most conspicuously distinguishes them from other Indo-European linguistic groups is their loss of the original Indo-European sound "P". Thus, a Latin, Greek, and Sanskrit word containing an initial or medial P will appear in the Celtic language family without it (for example, Latin porcus, Goidelic orc). The Goidelic and Brythonic groups of Celtic languages differ in that Goidelic preserves the velar element of the Indo-European labiovelar qu sound (later written c), whereas Brythonic renders this sound as p. Thus Irish cuig or coo-ig (or cuig), "five" corresponds to Welsh pump.
The rules of pronunciation in all the Celtic languages are extremely complicated; the spelling generally does not correspond to the pronunciation, and initial consonants change according to the final sound of the preceding word. For example, in Irish, fuil is "blood," but "our blood" is ar bhfuil. In Welsh tad ("a father") becomes fy nhad for "my father," ei thad for "her father," and i dad for "his father."
All modern Celtic languages use the Roman alphabet. They have only two genders, feminine and masculine; adjectives usually follow nouns. Like some non-Indo-European languages they use verbal nouns instead of present participles, always begin sentences with the verb, and express agency by means of the impersonal passive.
Breton, Cornish, Welsh