2. To make something certain: Winning the literary award should assure Paulette's publisher that the novel will be a success.
2. To make safe or secure: The government took steps to ensure the people that they would be safe from tyranny and terrorism.
3. To make or to take steps to provide for the safety of an object, individual, or situation: Shoveling snow after a snowfall was a way to ensure the safety of people walking on the sidewalks.
Heath, the owner of the new house, tried to insure it for $500,000.2. To take steps or precautions for the safety of a situation; often done in an anticipatory or precautionary manner: Nadine bought a bag of sand for the sidewalk before the major storm to insure she was prepared for any icy conditions.
Jody and Trent always try to take great care to insure the safety and security of their home.
Apparently assure, ensure, and insure all include the meaning "to make secure or certain". The use of assure refers to a person as in the sense of "to set the mind at ease"; as "Krista wanted to assure her employer that she was ready to handle the new assignment".
A person can ensure that there will be prompt delivery of an item while insure is the only proper verb to use when someone means "to protect against loss".
So, although ensure and insure can be interchangeable in some situations, insure is normally used in American English in the sense of "to guarantee people or property against the risk of physical harm, damage, or loss" as when people have health insurance, property insurance, etc.
Everyone should ensure that he or she will insure a new car before driving it off the sale's lot.