fem. proper name, popularized, by Macpherson (1761). It is identical to a Scots Gaelic word for "wine" (and thus perhaps from the same source as  vine), but it is sometimes said to be from Scots Gaelic fionn "white" also "fair" (of complexion or hair), from Old Irish find, from Proto-Celtic *windos "white," which would make it cognate with Welsh gwyn (as in Gwendolyn).

1570s, originally used of the great auk of Newfoundland (now extinct; the last two known birds were killed in 1844); the shift in meaning to the Antarctic swimming bird (which looks something like it, observed by Drake in Magellan's Straits in 1578) is from 1580s. The word itself is of unknown origin, though it often is asserted to be from Welsh pen "head" (see pen-) + gwyn "white" (see Gwendolyn). The great auk had a large white patch between its bill and eye. The French and Breton versions of the word ultimately are from English. A similarity to Latin pinguis "fat (adj.), juicy," figuratively "dull, gross, heavy," has been noted.