astomatous,a.|əˈstɒmətəs| [see next.] Having no mouth; applied in Zool. to the Astomata or ‘mouthless’ animals, a division of the Protozoa, comprising the Gregarindæ and Rhizopoda. 1855Owen Inv.Anim. 669 Astomatous Infusoria..have no true or determinate mouth.