A dragonfly is an insect belonging to the infraorder Anisoptera (from Greek ανισος anisos, "uneven" + πτερος pteros, "wings", because the hindwing is broader than the forewing).

It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body. Dragonflies can be mistaken for the related group, damselflies, which are similar in structure though usually lighter in build; however, adults can be differentiated by the fact that the wings of most dragonflies are held away from, and perpendicular to, the body when at rest.