Is it ensure, insure, or assure?
c.1200, delit, from Old French delit "pleasure, delight, sexual desire," from delitier "please greatly, charm," from Latin delectare "to allure, delight, charm, please," frequentative of delicere "entice" (see delicious). Spelled delite until 16c. when it changed under influence of light, flight, etc.
c.1200, deliten, from Old French delitier (see delight (n.)). Related: Delighted; delighting.