"something that absorbs a blow, apparatus for deadening the concussion between a moving body and that against which it strikes," 1835, agent noun from obsolete verb buff "make a dull sound when struck" (mid-16c.), from Old French bufe "a blow, slap, punch" (see buffet (n.2)). The figurative sense of "anything that prevents impact or neutralizes the shock of impact of opposing forces" is from 1858.
"lessen the impact of," 1886, from buffer (n.). Related: Buffered; buffering.
"one who or that which polishes by buffing," 1854, agent noun from buff (v.).
1670s, "glass filled to the brim;" perhaps from notion of bumping as "large," or from a related sense of "booming" (see bump (v.)). The meaning "anything unusually large" (as in bumper crop) is from 1759, originally slang. The agent-noun meaning "buffer of a car" is from 1839, American English, originally in reference to railway cars; 1901 of automobiles, in the phrase bumper-to-bumper, in reference to a hypothetical situation (it was used of actual traffic jams by 1908).