mount (v.)
c.1300, "to mount a horse;" mid-14c., "to rise up, ascend; fly," from Old French monter "to go up, ascend, climb, mount," from Vulgar Latin *montare, from Latin mons (genitive montis) "mountain" (see mount (n.)). Meaning "to set or place in position" first recorded 1530s. Sense of "to get up on for purposes of copulation" is from 1590s. Related: Mounted; mounting.
mount (n.2)
"that on which something is mounted," 1739, from mount (v.). The colloquial meaning "a horse for riding" is first recorded 1856.
mount (n.1)
"hill, mountain," mid-13c., from Anglo-French mount, Old French mont "mountain;" also perhaps partly from Old English munt "mountain;" both the Old English and the French words from Latin montem (nominative mons) "mountain," from PIE root *men- "to stand out, project" (cognates: Latin eminere "to stand out;" Sanskrit manya "nape of the neck," Latin monile "necklace;" Old Irish muin "neck," Welsh mwnwgl "neck," mwng "mane;" Welsh mynydd "mountain").