Meaning

verb hold back within

verb allow to remain in a place or position or maintain a property or feature

verb secure and keep for possible future use or application

originFrom Late Middle English reteinen, retein (“to continue to keep, retain; to continue to possess; to possess; to contain; to draw back, retire; to hold back, restrain; to keep in mind, remember; to take back, repossess; to appoint; to engage in one’s service, employ, hire”) [and other forms], from Anglo-Norman reteiner, retenir [and other forms], Middle French retenir, and Old French retenir (“to…

Etymology from Wiktionary, CC BY-SA 3.0