buffer (n.1)

"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)). 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.).