From Latin 'civis' (community member), from PIE *key- (to settle) — same root as 'city,' 'civil,' and 'civilization.'
A legally recognized member of a state or nation, entitled to its rights and subject to its obligations.
From Anglo-French 'citezein,' alteration of Old French 'citeain' (city-dweller, citizen), from 'cité' (city), from Latin 'cīvitātem' (accusative of 'cīvitās,' citizenship, community, state), from 'cīvis' (citizen, member of a community). The PIE root is likely *ḱey- (to lie down, to settle, to be at home). A citizen was originally one who belonged to a settlement