ensure
en.sure \in-'shu.(*)r\ vt [ME ensuren, fr. AF enseurer, prob. alter. of OF aseu:er] : to make sure, certain, or safe : GUARANTEE an outcome sure. ENSURE implies a making certain and inevitable; INSURE stresses the taking of necessary measures beforehand to make a result certain or provide for any probable contingency; ASSURE implies a making sure in mind by removing all doubt and suspense; SECURE implies action taken to guard against attack or loss SYN syn ENSURE, INSURE, ASSURE, SECURE mean to make
Webster's English Dictionary