What is "eurystheus"

In Greek mythology, Eurystheus (; meaning "broad strength" in folk etymology and pronounced ) was king of Mycenae, one of three Mycenaean strongholds in the Argolid, although other authors including Homer and Euripides cast him as ruler of Argos: Sthenelus was his father and the "victorious horsewoman" Nicippe his mother, and he was a grandson of the hero Perseus, as was his opponent Heracles. He was married to Antimache, daughter of Amphidamas.