Yellow jacket Meaning, Definition & Usage

  1. noun a barbiturate (trade name Nembutal) used as a sedative and hypnotic and antispasmodic
    pentobarbital; pentobarbital sodium; Nembutal.
  2. noun small yellow-marked social wasp commonly nesting in the ground
    yellow hornet; Vespula maculifrons.

WordNet

Definitions
  1. (Zoöl.), any one of several species of American social wasps of the genus Vespa, in which the color of the body is partly bright yellow. These wasps are noted for their irritability, and for their painful stings.

Webster 1913