Aloadae (əlōˈədē) [key] or Aloidae ălōĪˈdē, in Greek mythology, two giants who warred against the Olympian gods. Their names were Otus and Ephialtes, and they were sons of Aloeus' wife by Poseidon. They tried to reach heaven to overthrow the gods by piling Mt. Ossa on Mt. Olympus and Mt. Pelion on Mt. Ossa. Some said they were killed by Apollo, others said they killed each other while shooting at a hind sent by Apollo. For their wickedness they were condemned to eternal torture in Tartarus. Thus the phrase "to pile Pelion on Ossa" means to attempt an enormous but fruitless task.
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