Zoology. (With capital initial.) A class of invertebrate animals; formerly (as by Linnæus) made to comprise the whole of the division now called Arthr…

With plural (or occasionally singular) agreement: a very large and diverse invertebrate phylum (or superphylum) that comprises insects and…

Zoology. The thin, often waxy outermost layer of the cuticle of an insect or other arthropod. Cf. exocuticle, n. a, endocuticle, n. a.