Quick definitions from WordNet (assure)
▸ verb: assure somebody of the truth of something with the intention of giving the listener confidence ("I assured him that traveling to Cambodia was safe")
▸ verb: inform positively and with certainty and confidence
▸ verb: make a promise or commitment
▸ verb: cause to feel sure; give reassurance to ("The airline tried to reassure the customers that the planes were safe")
▸ verb: make certain of
▸ verb: be careful or certain to do something; make certain of something
▸ Also see assure
▸ verb: assure somebody of the truth of something with the intention of giving the listener confidence ("I assured him that traveling to Cambodia was safe")
▸ verb: inform positively and with certainty and confidence
▸ verb: make a promise or commitment
▸ verb: cause to feel sure; give reassurance to ("The airline tried to reassure the customers that the planes were safe")
▸ verb: make certain of
▸ verb: be careful or certain to do something; make certain of something
▸ Also see assure