Has this happened to you? As an English learner we all know the pitfalls of homonyms, but what happens when you encounter words which have the same cognate, a thesaurus tells us they all are synonyms, but you know instinctively they must somehow have different meanings?

As an experiment, try looking up the word ensure. You will find that the words assure, insure, and secure are all listed as synonyms. Moreover, they all have the same Latin derivation, securus, which means safe. In Latin, se means without, and curus means care. Literally, then, to be secure is to be without cares or worries. More significantly, the implication is that these words essentially mean the same thing. That would be a reasonable conclusion, and it would be completely wrong.

The differences in these words come from how they are used. Your thesaurus might (accurately) tell you that all four are synonymous, but the actual application of each word in a sentence or phrase will determine which word is appropriate.

In fact, these four words are among the most commonly misapplied words in the English language. Let’s take a closer look at the subtle differences between them.

Ensure: This is a verb used with an object given as a guarantee, or promise with respect to a specific event, situation, or condition. “I will deliver the envelope myself, just to ensure that you receive it.” If you remember the rule that ensure begins with an e, and guarantee ends with an e, you should have no problem knowing when to use this word.

Assure: This is also a verb used with an object, given as a statement of confidence to a person, animal, or group of beings. “I assure you that I will deliver that envelope before your meeting begins.” To assure anything is to verbalize a statement of certainty to something that’s alive. Assure and alive both begin with the letter a.

Insure: This is yet another verb used with an object used only in matters of loss, harm, or instability. “You want to be insured, so that you have a steady income, no matter what happens.” At one time, insure and ensure were considered interchangeable, but most rule books now make a clear distinction. Insure should be used only when referring to income or financial and personal risk. Both insure and income begin with the letter i.

Secure: This is an adjective meaning, as stated previously, free from harm, worries, or fear. It is applied to the actual possession of something. “I hope that once you have the envelope you will feel secure.”

“The contents of this envelope are your best insurance against losing your fortune. I will deliver the envelope myself, just to ensure that you receive it. I assure you that I will deliver the envelope before the meeting begins. I hope that once you have the envelope, that you will feel secure.”

I know, I know! This is precisely why English can be so maddeningly difficult to learn. However, once you discover the subtle differences between words like these, and know how to use them, the feeling of accomplishment is wonderful. I assure you!