invertebrate

adj. having no backbone

n. animal which has no backbone

Invertebrate is an English word that describes any animal without a spinal column. The group includes 97% of all animal species — all animals except those in the Chordate subphylum Vertebrata (fish, reptiles, amphibians, birds and mammals).Carolus Linnaeus' Systema Naturae divided these animals into only two groups, the Insecta and the Vermes.  Jean-Baptiste Lamarck, who was appointed to the position of "Curator of Insecta and Vermes" at the Muséum National d'Histoire Naturelle in 1793, both coined the term "invertebrate" to describe such and divided the original two groups into ten, by splitting off Arachnida and Crustacea from the Linnean Insecta, and Mollusca, Annelida, Cirripedia, Radiata, Coelenterata and Infusoria from the Linnean Vermes. They are now classified into over 30 phyla, from simple organisms such as sponges and flatworms to complex animals such as arthropods and molluscs.
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adj. invertebrate, spineless

n. invertebrate, animal which has no backbone

(n.)
One of the Invertebrata.
  

(a.)
Destitute of a backbone; having no vertebrae; of or pertaining to the Invertebrata.
  

All animals other than those in the phylum Chordata. They do not possess a notochord or vertebral column. Examples are worms, corals, sponges, etc. The protochordates are sometimes called higher invertebrates.