late 14c., "suggest, propose, suppose, assume," from Old French poser "put, place, propose," a term in debating, from Late Latin pausare "to halt, rest, pause" (source also of Italian posare, Spanish posar; see pause (v.)). The Old French verb (in common with cognates in Spanish, Italian, Portuguese) acquired the sense of Latin ponere "to put, place," by confusion of the similar stems. Meaning "put in a certain position" is from early 15c. Sense of "assume a certain attitude" is from 1840; the transitive sense (as an artist's model, etc.) is from 1859. Related: Posed; posing.
"to puzzle, confuse, perplex," 1590s, earlier "question, interrogate" (1520s), probably from Middle French poser "suppose, assume," from Old French poser "to put, place, set" (see pose (v.1)). Also in some cases a shortening of English appose "examine closely," and oppose. Related: Posed; posing.
"act of posing the body," 1818, from pose (v.1), in a sense developed in the French cognate. Figuratively from 1884.