Definition of pistol shrimp in US English:

pistol shrimp

noun

  • Any of various marine shrimps of the families Alpheidae and Crangonidae (infraorder Caridea), having one enlarged chela which can be snapped shut with a loud concussion used for defence and for stunning prey; also called snapping prawn, snapping shrimp.

Origin

1930s; earliest use found in American Midland Naturalist.