early 15c., expressioun, "action of pressing out;" later "action of manifesting a feeling;" "a putting into words" (mid-15c.); from Late Latin expressionem (nominative expressio) "expression, vividness," in classical Latin "a pressing out, a projection," noun of action from past-participle stem of exprimere "represent, describe," literally "press out" (see express (v.)). Meaning "an action or creation that expresses feelings" is from 1620s. Of the face, from 1774. Occasionally the word also was used literally, for "the action of squeezing out." Related: Expressional.