(Science: zoology) An extensive artificial group of invertebrates, having all the parts arranged radially around the vertical axis of the body, and the various organs repeated symmetrically in each ray or spheromere.
It includes the coelenterates and the echinoderms. Formerly, the group was supposed to be a natural one, and was considered one of the grand divisions of the animal kingdom.
Origin: NL, fr. Radiatus, p. P. See Radiate.