1 JASTR
or jast, n. [Engl. yeast; mid. H. G. jest and gest; Germ. gischt; Ivar Aasen jest and jestr; akin to ostr (q. v.) = a cheese]:—yeast, leaven; jastri, dat., Nikd.: jast-ostr, m. a kind of cheese, Fms. vi. (in a verse): jast-rín, f., poët. the ‘yeasting-stream’ = poetry, song, Kormak: in mod. usage jastr means the skin on curdled milk, whence jastr-súr, adj. curdled, acid, of milk, Lex. Poët.; hence the mod. hjastr, n. a frothy, light work; það er mesta hjastr.