From Middle Welsh blwyð, from Proto-Brythonic *bluɨð, from Proto-Celtic *bleidū (“year”),[1] related to *bleidanī (the source of blwyddyn and Old Irish blíadain), possibly from Proto-Indo-European *bʰleyd- (“pale”), though the semantic connection is weak.[2] See also Lithuanian blaĩvas (“whitish, blue, sober”), Proto-West Germanic *blait, Albanian blehurë.
Celtic cognates include Cornish bloodh, Breton bloaz; Old Breton blened, Welsh blynedd.
blwydd f (plural blwyddi)
In Welsh, blwydd refers to age and is the word used for a single year and is also found after numbers. The plural blwyddi is little utilised. When referring to any other kind of year, the word is blwyddyn in the singular, blynyddoedd in the plural and the special form blynedd is used after numbers.
Unlike other nouns, blwydd takes a nasal mutation when it appears after the numbers pum, saith, wyth, naw, or deg.
radical | soft | nasal | aspirate |
---|---|---|---|
blwydd | flwydd | mlwydd | unchanged |
Note: Certain mutated forms of some words can never occur in standard Welsh.
All possible mutated forms are displayed for convenience.
R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke et al., editors (1950–present), “blwydd”, in Geiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic Studies