a comment on the text of any author, intended to explain his sense more fully, whether in the same language or in any other. (See the article Commentary.)

The word evidently comes from the Greek γλῶσσα, tongue, office of a gloss being to explain the text, as that of tongue is to unfold the feelings and sentiments of the mind.

GLOSS is likewise used to signify a literal translation, an interpretation of an author, word for word, in another language.