Original text - English - -acea Etymology

-acea
suffix denoting orders and classes in zoology, from L. -acea, neut. pl. of -aceus "belonging to, of the nature of" (enlarged from adj. suffix -ax, gen. -acis); neut. pl. because of a presumed animalia, a neuter plural noun. Thus, crustacea "shellfish" are *crustacea animalia "crusty animals." In botany, the suffix is -aceae, from the fem. pl. of -aceus, with reference to L. plantae, which is a fem. plural.