1. A general category of the kingdom Animalia (multicellular animals) including those phyla the members of which lack a notochord; all animals except vertebrates in the phylum Chordata.
The definition information for Invertebrata is provided by Stedman's. You can search our medical dictionary here.
Stedman's, part of Lippincott Williams & Wilkins, provides a comprehensive line of health-science publications for healthcare professionals and medical students.