Compose, Comprise…Po-tay-to, Po-tah-to…Right?

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Ask any group of word nerds to list their grammar pet peeves, and you won’t have to wait long before someone starts bemoaning the fact that no one knows the difference between compose and comprise these days.
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It’s true that about anywhere you look, the two terms seem to be used interchangeably by many writers. But are they the same? And if not, what’s the difference?
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Are they interchangeable?

According to Merriam-Webster, the two terms have actually been used synonymously since the eighteenth century.
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However, that usage is looked down on in most literary circles. So, while you could choose to treat them as the same word if you really want to, you should be aware of the bias against it among certain readers. And your chosen style and publisher may have something to say about it, too.
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What’s the difference?

Most people have no problem with how to use compose. In fact, their error usually lies in using comprise when compose is what they meant. They actually have mirror definitions.

Both terms refer to the relationship between a whole object or concept and its parts.
The parts compose the whole, while the whole is composed of the parts.

Many moving parts compose the engine of my car.
The engine of my car is composed of many moving parts.

The whole comprises the parts, and this second part is where it gets tricky. Comprised of is actually incorrect because comprise already means composed of. If you want to reverse the original statement, you would say that the parts are comprised in the whole.

The engine of my car comprises many moving parts.
Many moving parts are comprised in the engine of my car.

​Comprised of and comprised by are becoming increasingly more common because they sound fancier or more formal. It’s similar to the hypercorrective use of I and myself when the speaker should have used me.

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​Since most of us have no trouble with the standard usage of compose, I find that what helps me is to remember that comprise means is composed of.

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​Rebecca Miller is a professional copyeditor and general fan of all things having to do with the written word and the English language.
You can check out her website at Oakdale Editing or connect through Facebook, LinkedIn, Instagram, or Email.