1520s, "manner or style of expression," also "brief expression with some unity; two or more words expressing what is practically a single notion," from Late Latin phrasis "diction," from Greek phrasis "speech, way of speaking, enunciation, phraseology," from phrazein "to tell, declare, indicate, point out, show, inform," also passively (phrazomai), "indicate to oneself, think or muse upon, consider; think up, contrive; suppose, believe, imagine; perceive, observe."
The Greek verb is of uncertain origin; perhaps it is connected with phrenes "wits, senses, sanity," phrēn "the mind, the heart," literally "midriff, diaphragm" (see phreno-). The musical sense of "a short and somewhat independent passage from a piece" is from 1789. Phrase-book "collection of expressions peculiar to a language" is by 1590s.
"to put into a phrase, express by a particular phrase," 1560s; see phrase (n.). Related: Phrased; phrasing.