n. & v.
--n.
1. a substance added to dough to make it ferment and rise, esp. yeast, or fermenting dough reserved for the purpose.
2 a a pervasive transforming influence (cf. Matt. 13:33). b (foll. by of) a tinge or admixture of a specified quality.
--v.tr.
1. ferment (dough) with leaven.
2 a permeate and transform. b (foll. by with) modify with a tempering element.
Phrases and idioms:
the old leaven traces of the unregenerate state (cf.
1. Cor. 5:6-8).
Etymology: ME f. OF levain f. Gallo-Roman spec. use of L levamen relief f. levare lift