Definition of commentary:
(n) :
a series of comments or annotations; esp., a book of explanations or expositions on the whole or a part of the Scriptures or of some other work; a brief account of transactions or events written hastily, as if for a memorandum; -- usually in the plural; as, Caesar's Commentaries on the Gallic War
"this letter . . . was published by him with a severe commentary. -Hallam."