assure - verb

• make certain of
• inform positively and with certainty and confidence
• assure somebody of the truth of something with the intention of giving the listener confidence
• be careful or certain to do something; make certain of something
• cause to feel sure; give reassurance to
• make a promise or commitment

assure - thesaurus

ascertain   check   control   ensure   guarantee   insure   promise   reassure   secure   see   tell