yeast -
n. 1 a greyish-yellow fungous
substance obtained esp. from fermenting malt liquors and used as a fermenting agent, to raise bread, etc.
2 any of various unicellular fungi in which vegetative reproduction takes place by budding or fission.
yeastless adj. yeastlike adj. [OE gist, giest (unrecorded): cf. MDu. ghist, MHG jist, ON jæstr]
