Meaning

noun (chemistry) an ionic compound that resists changes in its pH

noun a neutral zone between two rival powers that is created in order to diminish the danger of conflict

noun an inclined metal frame at the front of a locomotive to clear the track

originAgent noun from obsolete verb buff (“make a dull sound when struck”) (mid-16c.), from Old French buffe (“blow”). The “boatswain's mate” sense is said to be popularly explained by the mate being a “buffer”, that is intermediary, between officers and men, but various other explanations have also been proposed.

Etymology from Wiktionary, CC BY-SA 3.0