Source : Webster's Revised Unabridged Dictionary (1913)

Lancer \Lan"cer\, n. [Cf. F. lancier.]
   1. One who lances; one who carries a lance; especially, a
      member of a mounted body of men armed with lances,
      attached to the cavalry service of some nations.
      --Wilhelm.

   2. A lancet. [Obs.]

   3. pl. (Dancing) A set of quadrilles of a certain
      arrangement. [Written also {lanciers}.]

Source : WordNet®

lancer
     n : (formerly) a cavalryman armed with a lance