Real Dictionary

percoid in American English
a fish of this order
of or belonging to a very large order (Perciformes) of bony fishes found in fresh and salt water, including the perches, basses, and sunfishes
adjective: belonging to the Percoidea, a group of acanthopterygian fishes comprising the true perches and related families, and constituting one of the largest natural groups of fishes

percoid in British English
adjective: of, relating to, or belonging to the Percoidea, a suborder of spiny-finned teleost fishes including the perches, sea bass, red mullet, cichlids, etc
noun: any fish belonging to the suborder Percoidea