Merriam-Webster Online Dictionary
yeast (noun)1.
a) a yellowish surface froth or sediment that occurs especially in saccharine liquids (as fruit juices) in which it promotes alcoholic fermentation, consists largely of cells of a fungus (as the saccharomyces, ), and is used especially in the making of alcoholic liquors and as a leaven in baking - Saccharomyces cerevisiae
b) a commercial product containing yeast fungi in a moist or dry medium
c) (1) a unicellular fungus that is present and functionally active in yeast, usually has little or no mycelium, and reproduces by budding
(2) any of various similar fungi
2.
archaic the foam or spume of waves
3.
something that causes ferment or activity - were all seething with the yeast of revolt J. F. Dobie
intransitive verb
- ferment froth
