Source : Webster's Revised Unabridged Dictionary (1913)

Canteen \Can*teen"\ (k[a^]n*t[=e]n"), n. [F. cantine bottle
   case, canteen (cf. Sp. & It. cantina cellar, bottle case),
   either contr. fr. It. canovettina, dim. of canova cellar, or,
   more likely, fr. OF. cant. corner, It. & Sp. canto. See 1st
   {Cant}.] (Mil.)
   1. A vessel used by soldiers for carrying water, liquor, or
      other drink. [Written also {cantine}.]

   Note: In the English service the canteen is made of wood and
         holds three pints; in the United States it is usually a
         tin flask.

   2. The sutler's shop in a garrison; also, a chest containing
      culinary and other vessels for officers.

Source : WordNet®

canteen
     n 1: a flask for carrying water; used by soldiers or travelers
     2: sells food and personal items to personnel at an institution
        or school or camp etc.
     3: a restaurant outside; often for soldiers or policemen [syn:
        {mobile canteen}]
     4: a recreation room in an institution
     5: restaurant in a factory; where workers can eat