"breed of short-legged dog originally bred in Wales for herding cattle," 1921, from Welsh corgi, from cor "dwarf" + ci "dog" (from PIE root *kwon- "dog").
As a noun, "the Britons," also "the Welsh language," both from Old English. The word survives in Wales, Cornwall, Walloon, walnut, and in surnames Walsh and Wallace. Borrowed in Old Church Slavonic as vlachu, and applied to the Rumanians, hence Wallachia. Among the English, Welsh was used disparagingly of inferior or substitute things (such as Welsh cricket "louse" (1590s); Welsh comb "thumb and four fingers" (1796), and compare welch (v.)). Welsh rabbit is from 1725, also perverted by folk-etymology as Welsh rarebit (1785).
Proto-Indo-European root meaning "dog."
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit svan-, Avestan spa, Greek kyōn, Latin canis, Old English hund, Old High German hunt, Old Irish cu, Welsh ci, Russian sobaka (apparently from an Iranian source such as Median spaka), Armenian shun, Lithuanian šuo "dog."
1785, an absurd perversion of (Welsh) rabbit, as if from rare (adj.) + bit (n.). See Welsh.