Commentary
late Middle English: from Latin commentarius, commentarium (adjective, used as a noun), from commentari, frequentative of comminisci ‘devise’.
wiktionary
From Middle French commentaire, from Latin commentārius, commentārium(“notebook”), compare French commentaire. See comment.
etymonline
commentary (n.)
early 15c., "series or collection of comments," from Medieval Latin commentarius "notebook, annotation; diary, memoir," noun use of adjective, "relating to comments," from Late Latin commentum ""comment, interpretation" (see comment (n.)). Perhaps the Medieval Latin noun is short for volumen commentarium. Especially "explanation of difficult and obscure passages in a book or other writing" (1530s). Meaning "historical narrative" is from c. 1600. Meaning "description of some public event" is from 1927.
