gnathostomata

from The Century Dictionary.

• noun A tribe of irregular echinoids having a central peristome surrounded by a perignathic girdle, the ambulacra all similar, and the jaws present but sometimes rudimentary. It includes both living and extinct genera.
• noun A name given by Haeckel to a superclass of vertebrates containing the forms with true jaws, (normally) two pairs of limbs, and double nostrils. Same as Gnathostomi and synonomous with Amphirhina.
• A group of entomostracous crustaceans, containing the phyllopods, copepods, and ostracodes, as a suborder of Entomostraca.
• A tribe of true cope-pods, having a completely segmented body and masticatory mouth-parts, and being for the most part not parasitic. It contains the families Cyclopidæ, Calanidæ, and Notodelphyidæ.

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

• noun comprising all vertebrates with upper and lower jaws