leaven

WOTD – 22 November 2009

English [edit]

Middle English levain, from Old French, from Late Latin levamen, instead of levamentum, ultimately from Latin levō (“I raise”).

leaven (plural leavens)

Any agent used to make dough rise or to have a similar effect on baked goods.
(figuratively) Anything that makes a general assimilating (especially a corrupting) change in the mass.
- Bible, Luke xii. 1
  
  Beware of the leaven of the Pharisees, which is hypocrisy.

any agent used to make dough rise

leaven (third-person singular simple present leavens, present participle leavening, simple past and past participle leavened)

(transitive) To add a leavening agent.
(transitive) To cause to rise by fermentation.
(transitive, figuratively) To temper an action or decision.
- 1992, Rudolf M. Schuster, The Hepaticae and Anthocerotae of North America: East of the Hundredth Meridian, volume V, page vii
  
  With fresh material, taxonomic conclusions are leavened by recognition that the material examined reflects the site it occupied; a herbarium packet gives one only a small fraction of the data desirable for sound conclusions. Herbarium material does not, indeed, allow one to extrapolate safely: what you see is what you get […]
To imbue; to infect; to vitiate.
- Milton
  
  With these and the like deceivable doctrines, he leavens also his prayer.

to add leavening

to cause to rise by fermentation