Available Definitions:
1) n. - Originally, an explanatory note in the margin of the Bible, so called because written after the text; hence, a marginal note; a comment.
2) n. - A short homily or commentary on a passage of Scripture; as, the first postils were composed by order of Charlemagne.
3) v. t. - To write marginal or explanatory notes on; to gloss.
4) v. i. - To write postils, or marginal notes; to comment; to postillate.