The word "comprise" deals with the relationship between a whole and its parts, but it is used commonly with two opposite meanings, "to consist of" and "to constitute," as shown in the following examples (along with a significant variant of each major sense):


It is recommended that legislative counsel not use the verb "comprise."

Instead, for meaning 1a, "consist of" or "is composed of" is recommended; for meaning 1b., "include" is recommended.

For meaning 2a., "constitute" is recommended; for form 2b., which is meaning 2a. in the passive voice, "consist of" or "is composed of," is recommended as "is constituted of" does not appear in Acts or regulations.


It appears that the English language is changing with regard to the meaning of "comprise," with the once non-standard "constitute" meaning becoming more and more common. It is undesirable for a word to be used in legislation when there is a lack of consensus about its meaning, for the following reasons.

First, there is the possibility of ambiguity, particularly between the "consist of" and "include" meanings: the use of "comprise" to mean "include" in some cases may raise the question for other cases, at least theoretically, whether parts mentioned are an exhaustive listing or only an inexhaustive one.

Second, it goes against principles of readability to use a word that is used differently by different people.

Third, the use of the "constitute" meaning, while common both in Acts and regulations and in the language at large, might still be criticized by some readers as non-standard English. The "include" meaning might also be criticized by some.

Despite these criticisms, usage guides are not in fact uniform in their advice about how acceptable these forms are (see Sources at the end of this article).

If any generalizations may be drawn from the guides cited under Sources, they are that Canadian sources seem to be more favourable than British ones toward the "include" meaning, and that the Oxford dictionaries are more tolerant of the "constitute" meaning than the other sources are. Nonetheless, the lack of consensus among usage guides and dictionaries about what is acceptable is itself evidence that this word is in a state of flux.

It may be that "comprise" is displacing the active form of the verb "compose": although "compose" is very common in the passive voice ("a deck is composed of 52 cards"), and although "compose" is held up by the usage guides as the correct alternative to the "constitute" meaning of "comprise," it is quite rare to encounter it in the active voice ("52 cards compose a deck"), while this meaning of "comprise" is very common ("52 cards comprise a deck"). This is true not only in the language at large but in Acts and regulations as well - the passive "composed of" is used more than 250 times there but the active "compose" less than 20 (and that in very limited contexts), while "comprise" is used about 100 times with this meaning.

Sources (chronological order)