There are various ways of saying that something consists of something else:

  • composed of
  • comprised of
  • contained in
  • consist of

Maybe there are more. Are there hard and fast rules when to use which or are they synonyms?

  • Ummm. In my neck of the woods we usually just say is. Commented May 20, 2011 at 13:36
  • @FumbleFingers: I don't understand. A book is pages?
    – musiKk
    Commented May 20, 2011 at 14:27
  • 1
    I was joking a bit, but yes - it is. More naturally, perhaps, an entry in a dictionary is one or more definitions, examples, and etymology. Commented May 20, 2011 at 14:40

2 Answers 2


Here are some thoughts:

  • "composed of" refers to the parts of a thing from the point of view of the subject
  • "comprising" or "comprises" (not "comprised of" though ardent descriptivists will gnash their teeth at me) can refer to either.
  • "contained in" refers to the container from the point of view of its constituent parts
  • "consist of" or "consists of" refers to the elements of a thing, with the added implication that these elements are sine qua non — without them, the thing would not be what it is.
  • In retrospect I think it was an error on my part to include contained in which has clearly nothing to do with the rest. Thank you for your answer. I hope others will provide feedback too. Otherwise it'll be a bit hard for me to say if it's correct or not.
    – musiKk
    Commented May 20, 2011 at 13:00
  • Even I won't gnash my teeth at you. "Comprised of" is arising from an error (like irregardless), and even if it could one day become an accepted standard (which it certainly could), at the moment you risk appearing as though you have a poor command of the finer points of English if you use this construction.
    – Kosmonaut
    Commented May 20, 2011 at 14:01
  • Unfortunately this question didn't get as much attention as I hoped. Or maybe this answer sums it up best? Anyway, I'll accept it because it's certainly useful.
    – musiKk
    Commented May 24, 2011 at 9:07

There are some works relating the relatively mature field of mereology to natural languages; Wikipedia barely mentions them. I am not an expert on this particular crossroads, but I'm afraid that the ambiguity of natural language won't let you find hard and fast rules as you request. "Parts: A Study in Ontology" by Simons 1987 is the work that I know best about this, and you may find it useful if you are interested in a detailed study of the matter.

  • +1 Just hang on. We need many more such answers around here.
    – Kris
    Commented Oct 21, 2012 at 10:21

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