Ensure and insure sound similar, and they have very similar meanings, but they are not synonyms. Don’t use ensure when you mean insure, and vice versa.

• Ensure means to make sure or guarantee something.

Example: I want to ensure that my horse remains tied to that fence otherwise I will have to walk home.

• Insure means to take measures to guarantee an outcome, such as an insurance policy. In most cases, only use insure when referring to financial protection.

Example: I will insure my horse in case he is hit by a car while he’s running away from me.

To throw another spanner into the mix, how about ‘assure’?

It sounds a little bit like ensure and insure but it is doesn’t mean the same as either of them. Assure means to convince someone that something is true.

Example: I can assure you that my horse does not hate me, he just prefers to be at home.