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.