From the Greek ευρί — "wide" and the Greek βίον — "living".

Eurybionts are hydrobionts that are able to live under significant changes in environmental conditions and have a broad ecological value. For example, the inhabitants of the marine area endure regular drainage at low tide, strong warming in summer and cooling in winter. Animals living in areas with continental climates are able to tolerate significant seasonal variations in temperature, humidity and other natural factors. Eurybionts are usually characterised by larger home ranges than their stenobiont counterparts.

Oocysts of parasitic protozoa, larvae and eggs of some nematodes are very resistant to freezing, desiccation and many poisons, which allows them to remain viable for a long time. In some crustaceans (e.g. land crabs), the larvae are aquatic and the adults terrestrial.