The Collaborative International Dictionary of English v.0.48:

Lance \Lance\ (l[a^]ns), n. [OE. lance, F. lance, fr. L. lancea;
   cf. Gr. lo`gchh. Cf. Launch.]
   1. A weapon of war, consisting of a long shaft or handle and
      a steel blade or head; a spear carried by horsemen, and
      often decorated with a small flag; also, a spear or
      harpoon used by whalers and fishermen.
      [1913 Webster]

            A braver soldier never couched lance. --Shak.
      [1913 Webster]

   2. A soldier armed with a lance; a lancer.
      [1913 Webster]

   3. (Founding) A small iron rod which suspends the core of the
      mold in casting a shell.
      [1913 Webster]

   4. (Mil.) An instrument which conveys the charge of a piece
      of ordnance and forces it home.
      [1913 Webster]

   5. (Pyrotech.) One of the small paper cases filled with
      combustible composition, which mark the outlines of a
      figure.
      [1913 Webster]

   6. (Med.) A lancet.
      [PJC]

   Free lance, in the Middle Ages, and subsequently, a knight
      or roving soldier, who was free to engage for any state or
      commander that purchased his services; hence, a person who
      assails institutions or opinions on his own responsibility
      without regard to party lines or deference to authority.
      See also freelance, n. and a., and freelancer.

   Lance bucket (Cavalry), a socket attached to a saddle or
      stirrup strap, in which to rest the but of a lance.

   Lance corporal, same as Lancepesade.

   Lance knight, a lansquenet. --B. Jonson.

   Lance snake (Zool.), the fer-de-lance.

   Stink-fire lance (Mil.), a kind of fuse filled with a
      composition which burns with a suffocating odor; -- used
      in the counter operations of miners.

   To break a lance, to engage in a tilt or contest.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

lance corporal \lance" cor`por*al\, n.
   1. A lancepesade.
      [PJC]

   2. An enlisted member of the United States Marine Corps
      ranking between a private first class and a corporal.
      [PJC]

   3. The lowest rank of corporal; -- a term used in the British
      military. --RHUD
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Lancepesade \Lance`pe*sade"\, n. [F. lancepessade, lanspessade,
   anspessade, It. lancia spezzata a broken lance or demilance,
   a demilance roan, a light horseman, bodyguard.]
   An assistant to a corporal; a private performing the duties
   of a corporal; -- called also lance corporal. [Obsolete]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Corporal \Cor"po*ral\ (k[^o]r"p[-o]*ral), n. [Corrupted fr. F.
   caporal, It. caporale, fr. capo head, chief, L. caput. See
   Chief, and cf. Caporal.] (Mil.)
   A noncommissioned officer, next below a sergeant. In the
   United States army he is the lowest noncommissioned officer
   in a company of infantry. He places and relieves sentinels.
   [1913 Webster]

   Corporal's guard, a detachment such as would be in charge
      of a corporal for guard duty, etc.; hence, derisively, a
      very small number of persons.

   Lance corporal, an assistant corporal on private's pay.
      --Farrow.

   Ship's corporal (Naut.), a petty officer who assists the
      master at arms in his various duties.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lance corporal
    n 1: an enlisted man in the marine corps ranking above a private
         first class and below a corporal