The Collaborative International Dictionary of English v.0.48:

Buffer \Buff"er\ (b[u^]f"[~e]r), n. [Prop a striker. See
   Buffet a blow.]
   1. (Mech.)
      (a) An elastic apparatus or fender, for deadening the jar
          caused by the collision of bodies; as, a buffer at the
          end of a railroad car.
      (b) A pad or cushion forming the end of a fender, which
          receives the blow; -- sometimes called buffing
          apparatus.
          [1913 Webster]

   2. One who polishes with a buff.
      [1913 Webster]

   3. A wheel for buffing; a buff.
      [1913 Webster]

   4. A good-humored, slow-witted fellow; -- usually said of an
      elderly man. [Colloq.] --Dickens.
      [1913 Webster]

   5. (Chem.) a substance or mixture of substances which can
      absorb or neutralize a certain quantity of acid or base
      and thus keep the degree of acidity or alkalinity of a
      solution (as measured by pH) relatively stable. Sometimes
      the term is used in a medical context to mean antacid.
      [PJC]

   6. (Computers) a data storage device or portion of memory
      used to temporarily store input or output data until the
      receiving device is ready to process it.
      [PJC]

   7. any object or person that shields another object or person
      from harm, shock, or annoyance; as, the President's staff
      is his buffer from constant interruptions of his work.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Buffing apparatus \Buff"ing ap`pa*ra"tus\
   See Buffer, 1.
   [1913 Webster]