THESAURUS
Ensure
arm, armor, arrange, ascertain, assure, attest, back, be sponsor for, bless, bond, certify, champion, cinch, clear up, clinch, cloak, compass about, confirm, copyright, countersecure, cover, cushion, decide, defend, determine, dismiss all doubt, effect, endorse, establish, fence, fend, find out, fix, get at, guarantee, guaranty, guard, harbor, haven, insure, keep, keep from harm, make certain, make no doubt, make no mistake, make safe, make sure, make sure of, nail down, nestle, patent, police, protect, provide, reassure, register, remove all doubt, ride shotgun for, safeguard, screen, secure, see that, see to it, set at rest, set out, settle, shelter, shield, shroud, sign, sign for, sort out, sponsor, stand behind, stand up for, subscribe to, undersign, underwrite, warrant
ROGET THESAURUS
Ensure
Certainty
VB
be certain, stand to reason, render certain, insure, ensure, assure, clinch, make sure, determine, decide, set at rest, make assurance double sure, know, dogmatize, lay down the law.