assure, ensure, or insure? These three words are sometimes confused. The most common meaning of the verb to assure is ‘to inform (somebody) positively’: I assured her that she had nothing to worry about. Assure can also mean ‘to make certain or safe’ – but in this sense it is mainly found in the passive or adjectival form: Their success is assured; Rest assured that we will do all we can to help you. The verb generally used in the active form to mean ‘to make (something) certain’ is ensure (often spelt insure in American English): Our first duty is to ensure the safety of the passengers. Insure refers simply to making arrangements to obtain financial compensation in the event of accident or loss: The painting should be insured for at least a million pounds