1 firn
n. pl. (mod. firni), [Ulf. fairina = αἰτία], an abomination, shocking thing; mæltu margir at slíkt væri mikil firn, Nj. 156, Fs. 62, Sturl. i. 12, Fms. vi. 38, Gullþ. 13; svá miklum firnum, Eg. 765; f. ok endemi, or heyr á firn, what a monstrous thing! Fms. vii. 21, 25: the saying, firnum nýtr þess er firnum fær, cp. the Lat. ‘male parta male dilabuntur,’ Fbr. 28, Grett. 16 new Ed.: gen. pl. firna-, used as a prefix to adjectives and nouns, shockingly.
2 firn
COMPDS: firnadjarfr, firnafrost, firnafullr, firnaharðr.
3 firn
II. in mod. usage, firni = a great deal, a lot; firnin o:ll, a vast lot.