Compose and comprise sound similar, and they have similar meanings. At the same time, the word “compose” has many definitions that aren’t synonymous with “comprise”. You’ll never hear someone say “a musician comprised an opera” or “she comprised herself before stepping into the room.” Yet, it makes perfect sense to compose an opera or compose oneself. In this article, we’ll focus on a narrow scope. There’s an area of overlap between “comprise” and “compose” that causes many people to stumble over the correct word. We’re going to explain how to avoid confusion.
The following sentences clarify the basic use cases:
- The whole comprises the parts.
- The whole is composed of the parts.
- The parts compose the whole.
Both compose and comprise deal with the relationship between the parts and the whole. Let’s imagine a recipe. You may use either word to describe how the parts of the recipe relate to the whole; however, the English language requires that you use them differently. When the subject of the sentence is the whole, you can use the word “comprise” or the passive phrase “is composed of”. In this context, comprise means “contains” and “is composed of” means “is made of.”
The recipe comprises three eggs, a cup of sugar, and three cups of flour.
The recipe is composed of three eggs, a cup of sugar, and three cups of flour.
When the constituent parts are the subject of the sentence, you should stick to “compose”. In this context, compose means “make up.”
Three eggs, a cup of sugar, and three cups of flour compose the recipe.
Let’s try it again with 50 states (the parts) and the United States (the whole).
Here are examples of correct usage:
- The United States comprises fifty states.
- The United States is composed of fifty states.
- Fifty states compose the United States.
Although you may have heard people say “is comprised of,” this phrase can lead to mix-ups. We recommend always writing “comprise” in an active voice. The passive voice phrase is undergoing a contextual shift, and many people use “is comprised of” as a substitute for “is composed of.” Most grammarians take issue with this common mistake. The formal meaning of “is comprised of” should be the opposite: “is contained in” or “compose”. Because the passive phrase can cause misunderstandings, careful writers avoid it.