Origin and history of summit

c. 1400, somet, "highest point, peak, apex" of a physical thing, from Old French somete "summit, top," diminutive of som, sum "highest part, top of a hill," from Latin summum, noun use of neuter of summus "highest" (from PIE root *uper "over").

The older form of the word in English is summity (late 14c.), from Old French summite, from Late Latin summitas.

Figuratively, of abstract things, from 1711. The meaning "meeting of heads of state" (1950) is from Winston Churchill's metaphor of "a parley at the summit" and the phrasing at the summit was usual in this sense at first; summit alone in this sense is by 1959, probably short for summit meeting (by 1955).