The story
Disputed. Possibly from keys (a Latin document from 1417 refers to Claves Mann and Claves Legis: the Keys of Mann and the Keys of Law); possibly from Norse verb kjósa, "to choose"; possibly from the Manx term kiare as feed, "twenty-four", because the House has always had 24 members.
Etymology from Wiktionary, CC BY-SA 4.0.