An order of insects comprising three suborders: Anisoptera, Zygoptera, and Anisozygoptera. They consist of dragonflies and damselflies.

The class Insecta, in the phylum ARTHROPODA, whose members are characterized by division into three parts: head, thorax, and abdomen. They are the dominant group of animals on earth; several hundred thousand different kinds having been described. Three orders, HEMIPTERA; DIPTERA; and SIPHONAPTERA; are of medical interest in that they cause disease in humans and animals. (From Borror et al., An Introduction to the Study of Insects, 4th ed, p1)

A family of very small viruses containing circular, single-stranded DNA and possessing no envelope. The modes of transmission are not known.