1 birkja
1. t, to bark, strip; b. við, Jb. 235, Stj. 177; cp. Gkv. 2. 12, birkinn viðr (= birki viðr?), Fms. viii. 33; b. hest, to flay a horse.
2 birkja
2. u, f. [Ivar Aasen byrkja], the sap of a young birch, sap, got by boring a hole in the bark and sucking; þeir átu safa ok sugu birkju við, they chewed the sprouts and sucked birch sap with it, Fms. viii. 33.