What is "robber gull"

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.)

1. A purse crab.

2. Any hermit crab.

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

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