Commonly Confused Words: Assure / Ensure / Insure

[chomiji]

In today's column, we'll examine a trio of easily confused and closely related words, with the help of the cast of C.J. Cherryh's science fiction novel Merchanter's Luck.

Even the most casual look at assure, ensure, and insure will show that these are similar words. In fact, the situation is even more extreme than you might think. The Oxford Dictionaries online edition tells us that all three started out as derivatives of the Old French assurer, which in turn comes from Latin roots that mean "to make or cause something to be without cares or concerns."

That definition is pretty close to the current dictionary definition of assure, which means essentially "to make someone sure of something":

The door was labelled Montero & Matsuo, Mercantile Finance and Insurance, in sober, respectable-looking letters. The office beyond was hushed and rich, with dark grey carpet, a sectional in deep blue, and a receptionist at a forbidding and gleaming black desk.

"This can't be us, Allie," said Curran. Behind him, Deirdre and Neil nodded, silent and uneasy.

Allison gave Sandor a smile that was, she hoped, more confident than she felt. "This is the firm the Old Man told me about," she assured them all. "They should have all our info already."

The meaning of ensure is a bit more specific: to make certain that something will occur or that something will be the case:

"May we please see all your IDs?" said Matsuo, as they settled into their places at the conference table. It looked to be topped with real wood.

"We showed them to your man out there," said Curran, frowning.

"Of course you did," she said, her seamed face calm. "But given the nature of our business here, I need to ensure that you are exactly the persons whom you claim to be."

When we get to insure, things become very specific indeed. The most common meaning of this word is to set up financial compensation in the case of loss or damage of a person or thing:

Sandor was appalled at the figure that Matsuo suggested. "I've never insured any of my cargoes at that rate," he protested.

"But you do not now have the same sort of operation you did then," said Matsuo. "Now you are an associate of Dublin Again and their great mercantile operation. Your ship is no longer the tramp freighter Lucy but once again Le Cygne, of known family. You are far more of a target."

However, insure can be used in much the same way as ensure is used, especially in U.S. English:

At dinner, Sandor's head was still spinning with the cost of the new policy. "I don't know what you and Old Man Reilly were thinking, sending us to those fancy bloodsuckers," he said. He swallowed a mouthful of his drink and felt the vodka burn all the way down.

"We just want to insure that Le Cygne doesn't have any future mishaps," Allison protested. "What if we don't have Norway standing by next time we have a run-in with Mazianni?"

"The last time was all Norway's fault in the first place," said Curran, and Sandor was relieved that he hadn't had to bring it up it himself.

For clarity, though, it's probably best to use ensure when you're not talking specifically about a pre-arranged financial compensation—especially when such an arrangement is already in your readers' minds, as in the case of my tale of Le Cygne's crew.

To sum up: insure is best used when you're talking specifically about a formal compensation for damage or loss. Ensure is a little more general; it means to make certain that something will happen. Finally, to assure means to remove issues or doubts for someone; that is, to make something sure to someone or even to reassure someone. And of course, reassure is another member of this close family.

The blogger Grammar Girl suggest a mnemonic that may work for some of us:

So the quick and dirty tip is to use assure for things that are alive (remember that a is for alive), ensure to guarantee events and conditions (remember those two e's at the end of guarantee), … and insure for all of the above in financial contexts (remember the i is for income).

Sources

• assure [definition] (Oxford Dictionaries)
• ensure [definition] (Oxford Dictionaries)
• insure [definition]: Usage (Oxford Dictionaries)
• Assure Versus Ensure Versus Insure (Quick and DIrty Tips.com)