Source : Webster's Revised Unabridged Dictionary (1913)

Mugger \Mug"ger\, n. Also Muggar \Mug"gar\, Muggur \Mug"gur\
   [Hind. magar, fr. Skr. makara sea monster.]
   The common crocodile ({Crocodilus palustris}) of India, the
   East Indies, etc. It becomes twelve feet or more long.

Source : WordNet®

mugger
     n : a robber who takes property by threatening or performing
         violence on the person who is robbed (usually on the
         street)