burglar

from WordNet (r) 3.0 (2006)

burglar
    n 1: a thief who enters a building with intent to steal

from The Collaborative International Dictionary of English v.0.48

Burglar \Bur"glar\, n. [OE. burg town, F. bourg, fr. LL. burgus
   (of German origin) + OF. lere thief, fr. L. latro. See
   {Borough}, and {Larceny}.] (Law)
   One guilty of the crime of burglary.
   [1913 Webster]

   {Burglar alarm}, a device for giving alarm if a door or
      window is opened from without.
      [1913 Webster]

from Bouvier's Law Dictionary, Revised 6th Ed (1856)

BURGLAR. One who commits a burglary. (q. v.)