assure
/ə-ˈshu̇r/
verb
to make sure or certain : convince
to inform positively
to make certain the coming or attainment of : guarantee
glancing back to assure himself no one was following
ensure insure assure secure mean to make a thing or person sure. ensure insure, and assure are interchangeable in many contexts where they indicate the making certain or inevitable of an outcome, but ensure may imply a virtual guarantee , while insure sometimes stresses the taking of necessary measures beforehand
idiom
to make oneself sure or certain about something
He tried opening the door to assure himself that it was locked.
idiom
—used to say that one believes that something is certainly true, will happen, etc.