Invertebrates (Topical Term)

Henderson's dict. of biol. terms, 1979 (Invertebrata, invertebrates: a general term for all animal groups except the vertebrates, i.e. all animals without a backbone)

Britannica micro. (invertebrate: any animal that lacks a vertebral column. The taxonomic term Invertebrata, formerly used in contrast to Vertebrata (still a valid subphylum name), has no validity in modern classifications.)