A very extensive order of Annelida (segmented worms), characterized by the presence of lateral setæ, or spines, on most or all of the segments. They are divided into two principal groups: Oligochæta, including the earthworms and allied forms, and Polychæta, including most of the marine species.
In some systems of zoölogical classification, a prime division or branch of a phylum of the animal kingdom called Appendiculata, consisting of two classes, Oligochæta and Polychæta: in this sense contrasted with Rotifera (alone) and Gnathopoda (Arthropoda indiscriminately). [Little used.]
Ordinarily, an order or subclass of the class Annelida, with dorsal branchiæ and non-suctorial mouth.
A theory or system of social reform which contemplates a complete reconstruction of society with a more just and equitable distribution of property and labor In popular usage the term is often employed to indicate any lawless revolutionary social scheme See Communism Fourierism Saint Simonianism forms of socialism...