i Register
In some senses, postil is marked as archaic. Watch for register when choosing this word.
noun
A Bible commentary written in its margins.
A marginal note.
A short homily or commentary on a passage of Scripture.
A collection of homilies.
verb
To write marginal or explanatory notes on; to gloss.
postilled in the margin
To write postils, or marginal notes; to comment; to postillate.