Comprise and Compose

The Quick Answer
To comprise means to consist of (e.g., The cake comprises four slices.) Here are some quirks with to comprise:
  • Do not use of with comprise (e.g., It comprises of... ).
  • Avoid the construction is comprised of.
  • Avoid naming the constituent parts first (e.g., Four slices comprise the cake.)
To compose means to make up (e.g., Four slices compose the cake.)
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Comprise and Compose

There is often confusion over comprise and compose. The situation is not helped by ongoing debate about how to use comprise. If you stick to the guidelines below, you will be on safe ground.

Comprise

To comprise means to consist of or to be made up of. It is used to state that something is made up of smaller parts. Do not use the word of with comprise.

Examples:
  • The water molecule comprises two atoms of hydrogen and one atom of
    oxygen.
    • (The whole comprises the smaller parts.)
  • The water molecule comprises of two atoms of hydrogen and one atom of
    oxygen.
    • (Do not use the word of with comprise.)
  • Two atoms of hydrogen and one atom of oxygen comprise the water molecule.
    • (This is one of the areas under debate. Many advocate that comprise cannot be used to say the smaller parts make up the whole. They believe this is when compose should be used. If you adhere to this ruling too, you will never be on safe ground.)
  • The three wise monkeys comprise Mizaru (see no evil), Kikazaru (hear no evil), and Iwazaru (speak no evil).
  • The quadriceps femoris comprise the rectus femoris, the vastus medialis, the vastus intermedius and the vastus lateralis.

Is Comprised Of

The construction is comprised of (it correctly includes the word of) is considered by many to be non-standard English. To avert criticism, reword your sentence to avoid this construction.

Examples:
  • The water molecule is comprised of two atoms of hydrogen and one atom of oxygen.
    • (Some of your readers may frown at this version.)
  • The water molecule comprises two atoms of hydrogen and one atom of oxygen.
    • (This is the non-contentious version.)

Compose

To compose means to make up or to make. It is used to state that smaller parts make up the whole (i.e., the opposite of comprise). Do not use the word of with compose.

Examples:
  • Mercury, Venus, Earth, and Mars compose the inner planets.
  • The rectus femoris, the vastus medialis, the vastus intermedius and the vastus lateralis compose the quadriceps femoris.
  • Two atoms of hydrogen and one atom of oxygen compose the water molecule.

Is Composed Of

The construction is composed of (it correctly includes the word of) does not attract the same criticism as is comprised of

Examples:
  • USA is composed of 50 states.
  • The water molecule is composed of two atoms of hydrogen and one atom of oxygen.
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See Also

adverse or averse? affect or effect? appraise or apprise? avenge or revenge? bare or bear? complement or compliment? dependant or dependent? discreet or discrete? disinterested or uninterested? e.g. or i.e.? envy or jealousy? imply or infer? its or it's? material or materiel? poisonous or venomous? practice or practise? principal or principle? tenant or tenet? who's or whose?
Common errors and FAQs List of easily confused words