On a site similar to this one I answered a question and the OP made a comment which prompted me to complete my answer in an edit. I called it "an example" but I originally wanted to call it "supplement" or "complement". So, I wonder: is either of these titles correct in this context? Both? Both with a different nuance of meaning?

5 Answers 5


Supplement would refer to extra/additional information in this context. Complement refers to an item that completes or goes well with another item.

Personally, I'd be inclined to refer to an 'example' edit as a supplement to your original post. If the addition of an example makes your answer more complete though, you could certainly refer to it as a complement.

  • "Complement refers to an item that completes or goes well with another item." In my context, this is not the meaning I want to convey at all. However your comment reminds me that in economics there is the important notion of complementary good,a good jointly consumed with another good,like cars and gasoline. So yours is an interesting ... complementary remark! May 19, 2011 at 19:38
  • Ah, interesting stuff. I was not familiar with the term complementary good in economics, though obviously I understand the concept. We all learn something today, thanks :)
    – ajk
    May 19, 2011 at 19:55

AJ01 correctly defines the different meanings of the two words, but I think the main difference between them is that you shouldn't use complement at all unless you're very sure why you want it.

Complement is quite rare outside specialised contexts (music, geometry, computing, etc.). It doesn't really mean "goes together well with" - people just assume that because one of the few 'correct' common usages is, say, Mint sauce complements roast lamb. Where it means "makes complete", not just "is good with".

If only to avoid confusion with the totally unconnected compliment, I suggest you steer clear of this word. Supplement is perfectly valid for your example.

  • Could you please give an example or a reference for the use of complement in geometry? May 19, 2011 at 19:20
  • The complement of a 20 degree angle is 70 degrees, since together the two add up to 90 degrees.
    – ajk
    May 19, 2011 at 19:23
  • Thanks Jasper, that's a very nice complement to AJ01's remark.Actually, I knew this terminology for angles in French but didn't realize that you used exactly the same words in English. May 19, 2011 at 19:50
  • @FumbleFingers good point about the confusion between complement and compliment. Even if a word choice is correct and appropriate, sometimes it's worth avoiding if another option lets you sidestep common language pitfalls.
    – ajk
    May 19, 2011 at 19:58
  • Dang! I was hoping someone would ask about complements in music, so someone else would answer. I know they exist (something to do with octaves) but I don't know what & I'd rather find out here than on Google. I guess we know the computerese complements one and all though, so nobody mentions it. May 19, 2011 at 23:18

I'm not sure I'd use either in this case but complement would be my first choice of the two (given the context that what you provided was a completion.) Further addition/s could then be labeled supplement when / if you find an update is required due to a previous flaw or whatnot.

To be honest though, given the nature of sites like this, maybe I'd go for addendum. Reason being that I find requests on such sites to be like technical specifications, inasmuch as neither are often frozen in their requirements - 'completion' becomes a rarity, and additions seemingly perpetual.

  • Ah yes, addendum is indeed a nice and precise alternative. Jun 27, 2015 at 8:21

A Complement usually makes the word that it goes with complete or perfect. A Supplement, however, only helps that word. It is purely supplementary. Therefore it depends how you would like to make yourself mean.

In your question, either word would have been correct.
So if your answer makes your question perfected, then good. However, if it helps this your answer but doesn't necessarily perfect it, then put supplement.




A complement is always the response to incompleteness that provides the required essential part. For example: Soul is the complement for a human body to become a human being (without soul the body is not human being.


A supplement is always the response to extra needs or demand. For example: Spare Tyre is the supplement for any vehicle (without the spare tyre it’s possible to go anywhere but it’s essential to have one)

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