Leav"en (?), n. [OE. levain, levein, F. levain, L. levamen alleviation, mitigation; but taken in the sense of, a raising, that which raises, fr. levare to raise. See Lever, n.]
1.
Any substance that produces, or is designed to produce, fermentation, as in dough or liquids; esp., a portion of fermenting dough, which, mixed with a larger quantity of dough, produces a general change in the mass, and renders it light; yeast; barm.
2.
Anything which makes a general assimilating (especially a corrupting) change in the mass.
Beware of the leaven of the Pharisees, which is hypocrisy.
Luke xii. 1.
© Webster 1913.
Leav"en, v. t. [imp. & p. p. Leavened (?); p. pr. & vb. n. Leavening (?).]
1.
To make light by the action of leaven; to cause to ferment.
A little leaven leaveneth the whole lump.
1 Cor. v. 6.
2.
To imbue; to infect; to vitiate.
With these and the like deceivable doctrines, he leavens also his prayer.
Milton.
© Webster 1913.