A wide variety or range of something.
[Greek eurus, wide.]
Several terms in ecology refer to organisms that can tolerate a wide range of conditions, for example euryhaline (Greek halinos, of salt), tolerating a wide range of salinity; eurytopic (Greek topos, place), tolerating a variety of habitats or ecological conditions; eurythermal (Greek thermē, heat), tolerating a wide range of temperatures. These are usually contrasted with terms in steno-.
Other than these, eury- most frequently appears in the names of organisms, such as euryapsid (apsis, apsid-, arch), an extinct marine reptile of the Mesozoic period; eurypterid (Greek pteron, wing), a giant fossil marine arthropod; Eurycephalus, a genus of beetles.