Cal·y·don (kāl'ĭ-dŏn', -dən) An ancient city of west-central Greece north of the Gulf of Patras. According to legend, the Calydonian boar, a gigantic beast sent by Artemis to devastate the city, was slain by Meleager, the son of the king of Calydon. Cal'y·do'ni·an (-dō'nē-ən, -dōn'yən) adj. & n.