We define ensure as “to make sure, certain, or safe” and one sense of insure, “to make certain especially by taking necessary measures and precautions,” is quite similar. But insure has the …

Phrasal verb insure against something (Definition of insure from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)

Definition of insure verb in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

INSURE definition: to guarantee against loss or harm. See examples of insure used in a sentence.

If you insure yourself or your property, you pay money to an insurance company so that, if you become ill or if your property is damaged or stolen, the company will pay you a sum of money.

In both British and American English, if you insure your property, you pay money to a company so that if the property is lost, stolen, or damaged, the company will pay you a sum of money.

INSURE meaning: 1 : to buy insurance for (something, such as property or health); 2 : to provide insurance for (something, such as property or health)

Even though they can be synonyms, one way to make sure of correct usage is to use 'insure' to relate to financial matters and 'ensure' in the broader meaning of making certain or safe.

Phrasal verb insure against something (Definition of insure from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)

If you insure yourself or your property, you pay money to an insurance company so that, if you become ill or if your property is damaged or stolen, the company will pay you a sum of money. …