Believing that proper word usage is a significant part of good style, we wander slightly from our usual fare to discuss a construction frequently encountered in academic writing, the statement that “X is comprised of Y.”
The meaning of the phrase is generally evident: X is made up of Y. Unfortunately, this is not the principal (or preferred) meaning of the term comprise. Merriam-Webster’s Collegiate Dictionary (11th ed.) offers the following primary definition of comprise: “to include esp. within a particular scope.” On the basis of this definition, many argue that, just as one would never write that “X is included of Y,” one should likewise avoid the expression that “X is comprised of Y.”
Of course, few things in life and language are that clear-cut, and some writers (and even dictionaries) argue back that, given the frequent usage of comprise to mean “to consist of, be composed of” both recently and in times past, the construction “X is comprised of Y” should be regarded as an acceptable secondary use of the term.
The editors of the Chicago Manual of Style disagree, characterizing the construction “X is comprised of Y” as “poor usage” (§5.220). We concur. The English language possesses enough terms that actually mean what the construction intends to convey that we see no reason to stretch a term that means the opposite to communicate a given point. Remember: the whole comprises the parts, and the parts constitute or compose the whole.
Instead of reflexively writing that “X is comprised of Y,” authors should consider stating that “X consists of Y,” “X is composed of Y,” “X is constituted of Y,” or even “X is made up of Y.” Such careful usage of the English language will be no less clear to readers and will have the added virtue of signaling an informed understanding of the meaning of the term comprise.