yeast yeast /ˈjiːst/

noun

1. Any of various single-celled fungi that reproduce asexually by budding or division  ( yeast )
   any of various single-celled fungi that reproduce asexually by budding or division
   
   
2. A commercial leavening agent containing yeast cells; used to raise the dough in making bread and for fermenting beer or whiskey  ( barm , yeast )
   a commercial leavening agent containing yeast cells; used to raise the dough in making bread and for fermenting beer or whiskey