Meaning

noun a regular patron

noun a soldier in the regular army

noun a dependable follower (especially in party politics)

originFrom Middle English reguler, from Anglo-Norman reguler, Middle French reguler, regulier, and their source, Latin rēgulāris (“continuing rules for guidance”), from rēgula (“rule”), ultimately from Proto-Indo-European *h₃reǵ- (“move in a straight line”).

Etymology from Wiktionary, CC BY-SA 3.0