cét-

From Old Irish cét-, from Proto-Celtic *kentus (“first”), from Proto-Indo-European *ken- (“to begin”).

cét-

1. first

• Irish: céad
• Manx: kied
• Scottish Gaelic: ciad

• G. Toner, M. Ní Mhaonaigh, S. Arbuthnot, D. Wodtko, M.-L. Theuerkauf, editors (2019), “1 cét-”, in eDIL: Electronic Dictionary of the Irish Language

A conflation of two prefixes.

• The usual prefix meaning "first" is essentially a prefixed stem form of Proto-Celtic *kentus (“first”), from Proto-Indo-European *ken- (“to begin”). See also the related cétnae (“first”).
• A different prefix meaning "with", attested in only two or so word families, is from Proto-Celtic *kanta, derives from Proto-Indo-European *ḱóm (“with”), and is cognate with Welsh gan (“with”) and Ancient Greek κατά (katá, “against, downwards”).

cét- (pretonic ceta-)

1. first

   ‎cét- (“first”) + ‎cin (“crime”) → ‎cétchin (“first crime”)

   ‎cét- (“first”) + ‎aín (“fast”) → ‎cétaín (“Wednesday”, literally “first fasting”)

   ‎cét- (“first”) + ‎id- (“it”) (relative) + ‎do·rigni (“who have done”) → ‎cetid·deirgni (“who have done it first”)

   ‎cét- (“first”) + ‎ro·chreti (“who had believed”) → ‎ceta·ruchreti (“who had first believed”)

2. (rare) with

   ‎cét- (“with”) + ‎buith (“being”) → ‎cétbaid (“feeling”)

   ‎cét- (“with”) + ‎lúud (“moving”) → ‎cétluth (“cohabitation”)

   ‎cét- (“with”) + ‎·bí (“is, exists”) (habitual conjunct) → ‎ceta·bí (“feels”, literally “exist with”)

• This prefix, in the form cét, is attached to nouns, while ceta- is attached to relative verbs. When prefixed to nouns, lenition is triggered on the root word.
• The verbal prefixation of the prefix meaning "with" is one-of-a-kind, only occurring to make ceta·bí (“to feel”).

• Middle Irish: cét-
  • Irish: céad
  • Manx: kied
  • Scottish Gaelic: ciad

• G. Toner, M. Ní Mhaonaigh, S. Arbuthnot, D. Wodtko, M.-L. Theuerkauf, editors (2019), “1 cét-”, in eDIL: Electronic Dictionary of the Irish Language
• G. Toner, M. Ní Mhaonaigh, S. Arbuthnot, D. Wodtko, M.-L. Theuerkauf, editors (2019), “2 cét-”, in eDIL: Electronic Dictionary of the Irish Language
• G. Toner, M. Ní Mhaonaigh, S. Arbuthnot, D. Wodtko, M.-L. Theuerkauf, editors (2019), “ceta-, cita-, ciata-”, in eDIL: Electronic Dictionary of the Irish Language