In Greek mythology a cyclops (pronounced /ˈsaɪklɒps/), or kyklops (Greek Κύκλωψ), is a member of a primordial race of giants, each with a single eye in the middle of its forehead. The plural is cyclopes (pronounced : /saɪˈkloʊpiːz/) or kyklopes (Greek Κύκλωπες). In English, the plural cyclopses is also used. The name is widely thought to mean "round-" or "wheel-eyed". Hesiod describes one group of cyclopes and Homer describes another. In Hesiod's Theogony, Zeus releases three Cyclopes, the sons of Uranus and Gaia, from the dark pit of Tartarus. They provide Zeus's thunderbolt, Hades' helmet of invisibility, and Poseidon's trident, and the gods use these weapons to defeat the Titans. In a famous episode of Homer's Odyssey, the hero Odysseus encounters the Cyclops Polyphemus, the son of Poseidon and a nereid (Thoosa), who lives with his fellow Cyclopes in a distant country. The connection between the two groups has been debated in antiquity and by modern scholars.