reign: [13] Reign goes back via Old French reignier to Latin rēgnāre ‘be king, rule’, a derivative of rēgnum ‘kingship’ (source of English interregnum [16]). This was closely related to rēx ‘king’ (source of English regal, royal, etc), and also to regere ‘rule’ (source of English rector, regent, etc). => interregnum, regent