This entry tackles what you might call personal grammar peeves—mistakes that just drive you crazy, even though they are minor. Two that make my skin crawl are:
*comprised of
*hone in on

Unicorn phrases: these just don’t exist!

by | Sep 29, 2015

Comprise vs. compose & home vs. hone

This entry tackles what you might call personal grammar peeves—mistakes that just drive you crazy, even though they are minor. Two that make my skin crawl are:
*comprised of
*hone in on

Neither of these expressions is correct. 

If you don’t care about the explanation here, just know this. Don’t use “is comprised of” or “hone in on.” Replace these phrases with “is composed of” or “home in on,” respectively.

But you, dear reader, are of course very interested in why this is so. I’ll tackle these explanations one at a time, and in reading this post you’ll get a better, clearer sense of what four different words mean: comprise, compose, hone, and home. Let’s go.

Comprise vs. Compose

If you’re reading this blog, you’ve probably looked up the definition of comprise versus compose.

There’s lots of disagreement about how to use comprise, primarily because people don’t agree on its precise definition.

Does it mean “include,” “contain,” or “to be made up of”? These definitions mean roughly the same thing, but the subtle differences between them can captivate grammar nerds.

Let’s sidestep that debate and get to the practical: one thing you can quickly see is adding “of” to any of these ideas makes no sense. You would not say “included of,” “contained of,” or “to be made up of of.”

So, in short, don’t use “comprised of.”


My rule of thumb is to use comprise to indicate individual, identifiable constituent parts of a larger entity. Here are relationships for which comprise works:
A collective nation & its individual states
A university system & its individual/satellite campuses
A holding company & its disparate businesses

The idea here is that you are identifying all of the parts that make one identity. It is a way of defining the larger entity precisely.

“The University of Iowa system comprises three campuses.”

The Associated Press Stylebook helpfully defines comprise as meaning  “to include all of.” So, you use it when you are enumerating all of the parts of a collective whole.


Strictly speaking, compose means to create or to make, like “to compose a piece of music.” This is how we’ve ended up with “is composed of.” People use it to mean “to be made up of.”
“The University of Iowa system is composed of three campuses.”

That’s technically correct, though it often brings unnecessary fat with it (a “to be” verb plus a preposition). In other words, you’ve added fat without adding meaning. That said, using “comprise” can sound stilted or pedantic. Quite simply, in spoken word, most Americans say “is composed of,” not “comprises,” and I tend to favor making written text seem like written speech. In the end, I opt for one or maybe two uses of “comprise” per project.

For all the super grammar nerds out there, I do accept the inverse construction: “Three campuses comprise the University of Iowa” in which the constituent parts (“three campuses”) are the subject of the sentence and the larger entity (“University of Iowa”) is the direct object. Again, in my mind, “comprise” denotes the accumulation of all of the disparate parts that form a whole, and I don’t think there’s a ready, exact synonym for this idea in any other word in the English language. (In other words, I don’t think “comprise” exactly means “includes” or “contains.”) That said, the most common and accepted usage by far is the construction in which the larger entity is the subject of the sentence and the disparate parts are the direct object. And again, what everyone agrees on is that “is comprised of” makes no sense.

Hone in on vs. home in on

This one is easy. To hone means to sharpen, and to home means to focus.

It does not make sense to sharpen in on something. Rather you focus in on something.

Therefore, the phrase is “home in on,” not “hone in on.”


Use hone when you are talking about sharpening or refining, as in “I honed my writing skills by taking a great webinar.”

Get the most useful business writing tips!

Get the most useful business writing tips!

You have Successfully Subscribed!

Share This