Source : Webster's Revised Unabridged Dictionary (1913)

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.

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

Source : WordNet®

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