Merriam-Webster Collegiate Dictionary - buffer

 I. noun  Etymology: origin unknown  Date: 1749 slang British fellow, man; especially an old man  II. noun  Usage: often attributive  Etymology: buff, verb, to react like a soft body when struck  Date: 1835  1. any of various devices or pieces of material for reducing shock or damage due to contact  2. a means or device used as a cushion against the shock of fluctuations in business or financial activity  3. something that serves as a protective barrier: as  a. ~ state  b. a person who shields another especially from annoying routine matters  c. mediator 1  4. a substance capable in solution of neutralizing both acids and bases and thereby maintaining the original acidity or basicity of the solution; also a solution containing such a substance  5. a temporary storage unit (as in a computer); especially one that accepts information at one rate and delivers it at another  • ~ed adjective  III. transitive verb  (~ed; ~ing)  Date: 1845  1. to lessen the shock of ; cushion  2. to treat (as a solution or its acidity) with a ~; also to prepare (aspirin) with an antacid  3. to collect (as data) in a ~  IV. noun  Date: 1854 one that buffs