An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) A series of comments, explanations, or annotations (Dictionary.com).
2) An explanatory essay or treatise (Dictionary.com).

From M.E. commentaries (plural), from L. commentarium "notebook," noun use of neuter of commentarius, from comment(um), → comment, + -arium, → -ary.

Hâmatgân, from hâmat, → comment, + gân suffix forming plural entities, from Mid.Pers. -gânag, -gâna.