1. A grasshopper or locust with short antennae, a short-horned grasshopper: An acridid is one of several kinds of terrestrial plant eating insects of the family Acrididae with hind legs adapted for leaping and with short antennae, and which commonly migrate in swarms that strip the vegetation from large areas.

Acridids, or grasshoppers with short antennae, are related to the crickets (Gryllidae) and to the long-horned grasshoppers and katydids (Locustidae).
2. Any of various cicadas: The seventeen-year locust is considered to be an acridid.