Source : Webster's Revised Unabridged Dictionary (1913)

Robber \Rob"ber\, n.
   One who robs; in law, one who feloniously takes goods or
   money from the person of another by violence or by putting
   him in fear.

         Some roving robber calling to his fellows. --Milton.

   Syn: Thief; depredator; despoiler; plunderer; pillager;
        rifler; brigang; freebooter; pirate. See {Thief}.

   {Robber crab}. (Zo["o]l.)
   (a) A purse crab.
   (b) Any hermit crab.

   {Robber fly}. (Zo["o]l.) Same as {Hornet fly}, under
      {Hornet}.

   {Robber gull} (Zo["o]l.), a jager gull.

Source : WordNet®

robber fly
     n : swift predatory fly having a strong body like a bee with the
         proboscis hardened for sucking juices of other insects
         captured on the wing [syn: {bee killer}]