yellow jacket

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of several small wasps of the family Vespidae that have yellow and black markings and nest in the ground, in trees, or in buildings.

from The Century Dictionary.

• noun Any one of several species of true social wasps or hornets of the genus Vespa, which have the body more or less marked with yellow; any hornet, as V. crabro. See cut under hornet.
• noun In Australia, any one of several species of trees having a smooth, yellow bark, especially the yellow box, Eucalyptus melliodora, and the river gum, Eucalyptus rostrata.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun small yellow-marked social wasp commonly nesting in the ground
• noun a barbiturate (trade name Nembutal) used as a sedative and hypnotic and antispasmodic