"bottom, foundation, pedestal," early 14c., from Old French bas "depth" (12c.), from Latin basis "foundation," from Greek basis "step, pedestal," from bainein "to step" (see come). The military sense is from 1860. The chemical sense (1810) was introduced in French 1754 by French chemist Guillaume-François Rouelle (1703-1770). Sporting sense of "starting point" ia from 1690s, also "destination of a runner" (1812). As a "safe" spot in a tag-like game, suggested from mid-15c. (as the name of the game later called prisoner's base).

late 14c., "low, of little height," from Old French bas "low, lowly, mean," from Late Latin bassus "thick, stumpy, low" (used only as a cognomen in classical Latin, humilis being there the usual word for "low in stature or position"), possibly from Oscan, or Celtic, or related to Greek basson, comparative of bathys "deep." Figurative sense of "low in the moral scale" is first attested 1530s in English, earlier "servile" (1520s). Base metals (c.1600) were worthless in contrast to noble or precious metals.

"to place on a foundation," 1841, from base, n.. Related: Based; basing.