Postillate \Pos"til*late\, v. t. [LL. postillatus, p. p. of postillare.] To explain by marginal notes; to postil. Tracts . . . postillated by his own hand. --C. Knight. Postillate \Pos"til*late\, v. i. 1. To write postils; to comment. 2. To preach by expounding Scripture verse by verse, in regular order.