The verb assure has 6 senses (first 6 from tagged texts)
1. (21) guarantee, ensure, insure, assure, secure -- (make certain of; "This nest egg will ensure a nice retirement for us"; "Preparation will guarantee success!")
2. (9) assure, tell -- (inform positively and with certainty and confidence; "I tell you that man is a crook!")
3. (9) assure -- (assure somebody of the truth of something with the intention of giving the listener confidence; "I assured him that traveling to Cambodia was safe")
4. (6) see, check, insure, see to it, ensure, control, ascertain, assure -- (be careful or certain to do something; make certain of something; "He verified that the valves were closed"; "See that the curtains are closed"; "control the quality of the product")
5. (2) reassure, assure -- (cause to feel sure; give reassurance to; "The airline tried to reassure the customers that the planes were safe")
6. (1) promise, assure -- (make a promise or commitment)