13c., from O.Fr. monter "to go up, ascend, climb, mount," from V.L. *montare, from L. mons (gen. montis) "mountain" (see mount (n.)). Meaning "to set or place in position" first recorded 1530s. Sense of "to get up on (a horse, etc.) to ride" is from c.1500; "to get up on for
purposes of copulation" is from 1590s. The colloquial noun meaning "a horse for riding" first recorded 1856. Related: Mounted; mounting.
"hill, mountain," mid-13c., from Anglo-Fr. mount, from O.Fr. mont "mountain;" also partly from O.E. munt "mountain;" both the O.E. and the O.Fr. from L. montem (nom. mons, gen. montis) "mountain," from PIE base *men- "to stand out, project" (cf. Welsh mynydd "mountain").