The Collaborative International Dictionary of English v.0.48:

Porter \Por"ter\, n. [F. porteur, fr. porter to carry, L.
   portare. See Port to carry.]
   1. A carrier; one who carries or conveys burdens, luggage,
      etc.; for hire.
      [1913 Webster]

   2. (Forging) A bar of iron or steel at the end of which a
      forging is made; esp., a long, large bar, to the end of
      which a heavy forging is attached, and by means of which
      the forging is lifted and handled in hammering and
      heating; -- called also porter bar.
      [1913 Webster]

   3. A malt liquor, of a dark color and moderately bitter
      taste, possessing tonic and intoxicating qualities.
      [1913 Webster]

   Note: Porter is said to be so called as having been first
         used chiefly by the London porters, and this
         application of the word is supposed to be not older
         than 1750.
         [1913 Webster]