word-forming element denoting "belonging to, of the nature of," from Latin -aceus, enlarged form of adjectival suffix -ax (genitive -acis); see -acea. Especially in biology, "pertaining to X order of plants or animals."
Entries linking to -aceous
-acea
word-forming element in Modern Latin making names for orders and classes in zoology (Crustacea, Cetacea, etc.), from Latin -acea, neuter plural of -aceus "belonging to, of the nature of" (enlarged from adjectival suffix -ax, genitive -acis).
The names are thus formally adjectives, Latin animalia "animals" (a neuter plural noun) being understood. Thus Crustacea "shellfish" are *crustacea animalia "crusty animals."
In botany, the suffix is -aceae, from the fem. plural of -aceus, forming orders or families of plants (Rosaceae, etc.) with a presumed plantae "plants," which is a fem. plural.
carbonaceous adj.
1791, "pertaining to or consisting of charcoal or coal;" 1794, "pertaining to or consisting of carbon;" see carbon + -aceous.