yellow jacket

yellow jacket   n.  Any of several small wasps of the family Vespidae that have yellow and black markings and usually nest in the ground.

Main Entry: yellow jacket
Function: noun
1 : any of various yellow-marked social wasps (especially genus Vespula of the family Vespidae) that usually nestin the ground, aggressively defend their nests, and can sting repeatedly and painfully
2 : a yellow capsule containing a preparation of pentobarbital —usually used in plural