Compliment vs Complement

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I had an email at work recently which read “This new software will compliment the existing system.” Can you spot what’s wrong with that sentence?

If you get confused by the difference between compliment and complement, or if you’re unsure which to use when, read on.


Merriam-Webster defines a compliment as “an expression of esteem, respect, affection, or admiration; especially : an admiring remark”. It comes from Middle French, via the Italian complimento, and the Spanish cumplimiento, which originates from the Latin verb cumplir: to be courteous.

For example:

  • I was trying to pay that girl a compliment, but she ignored me.
  • Sometimes he blushes when you offer him a compliment.

In the plural, compliments can also mean best wishes. It is often used as “with compliments” such as on a compliments slip (a small piece of letter-headed paper, often used by companies for a quick note to a customer or client when a full sheet would be too large.) You also see the phrase “with compliments of the season” in greetings cards.

The verb “to compliment” is very similar, meaning “to pay a compliment to”. Note that it is a transitive verb so must have an object. For example:

  • Are you trying to compliment me, or trying to insult me?
  • When he complimented the girl on her dress, his friends laughed at him.


The adjective complimentary is closely related to the word compliment, and in this context it can mean either “expressing or containing a compliment” or “favourable” (Merriam-Webster):

  • My mother made some very complimentary remarks about my choice of shoes.
  • The new restaurant has a very complimentary write-up in the local newspaper.

Complimentary also has the meaning “free”, when something is given as a courtesy or favour:

  • Please accept these complimentary tickets.
  • I thought that the mini-bar was complimentary, but we were charged for our drinks.


The word complement comes from the same root as complete. It has nothing to do with being courteous, and comes directly from Middle English, from the Latin word complementum. Merriam-Webster’s first definition is “something that fills up, completes, or makes perfect”, and it can also be used to mean “the quantity, number, or assortment required to make a thing complete”, though can sound a little odd or old-fashioned in this context:

  • We had the full complement of pots and pans.
  • Our store does not have enough employees to work the required complement of hours.

Complement is often used in scientific, technical or academic areas of discourse, where the complement of X supplies what X is missing, thus making a complete whole. Examples of this usage are:

  • Complement good (economics)
  • Complementary colour (art)

You can find a fuller list in Wikipedia’s entry for the term Complement.

In everyday writing, complement is more often used as a verb. Again, it is a transitive verb:

  • The illustrations complement the text.
  • Our new software will complement the existing product.

So, my email correspondent should have written that “This new software will complement the existing system.” But I suspect she wouldn’t have replied to compliment me if I’d written back to point out the mistake…

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24 thoughts on “Compliment vs Complement”

  1. Hi

    It should be ‘everyday writing’; not ‘every day writing’. And colons should always follow complete sentences, not fragments.

    But thank you for this article. I see people mistake ‘complement’ for ‘compliment’ far too often.

  2. Hi Tarah,

    Well spotted on the “every day writing” — I’ve changed it to “everyday” now!

    I’m not so sure on the colon issue — I agree some guides do say colons should always follow an independent clause (ie. one that could stand alone as a sentence). However, there are numerous examples of colons NOT being used in this manner, eg. “Dear Sir:” at the start of a letter.

    If I find out a definitive answer, I’ll amend the colons, though!

  3. I regret to have to bring it to your attention, but “cumplir” is not a Latin verb and is not even in the form of any Latin verb inflection whatsoever. There is something amusing about people who laud themselves for being the sole remaining caretakers of English grammar and being so much more educated than the ignorant masses. However, language is dynamic and it is a futile task to try to preserve such a poorly constructed language as English in its modern state. After reading much of your site, I am disgusted by how much I have seen that is plain ignorant if not flat-out wrong. This kind of bullsh-t might fly in a high school English classroom, but keep this trash off the internet.

  4. Your detail, though brief, indeed complements the topic. A likewise on ‘lay-lie’ is appreciated.

  5. French: plier = to fold or bend
    Latin: plica = a fold

    Latin: plenus = full

    So to complement means to make something complete or full, and to compliment means to be polite, compliant as opposite to rude, stiff or unbending.

    At least that explanation works for me.

  6. Silly, Silly Gbotgirl! A sentence should not begin with a preposition such as “From”! ;P Thanks for posting this because not enough people care to tend to our language so we are becoming a bunch of mindless, ineloquent drones.

  7. For me, an easy way of determining which to apply, using an associative memory trick, is to remember that the only difference between the two words is an ‘i’ or an ‘e’. So:

    Compliment contains the ‘i’ – which is the beginning of an ‘insult’. A compliment is the opposite of an insult.

    Complement contains the ‘e’ which is the begin of the word ‘equal’. Something which complements something else has a kind of equality. Salt complements pepper, for example.

    Works for me – hope it works for those of you who like to use mnemonics!

  8. Complementary colour(lovely “old English spelling and nice to see used) has two meanings in art.

    1. To blend or go with another colour or colours.

    2. Actually means “opposite” or “directly across from” on the colour wheel. It is used in “old master” paintings as opposite transparent colour (one over the other) giving a visual “glow” or with flat “side by side” fields of colour to create a line that vibrates.

    It also seem to me that a colour may “compliment,” enhance or “give praise” with its new presence by sacrifice of itself for the greater good.

    I believe the intent is variable and in some cases intended as artist’s license.

    As an amusement, the extreme authority of “spell check” always thinks that “colour” is misspelled along with judgement and some other old spellings.

  9. To Don St Clair: Heh heh! I’m amused by your comment that ‘colour’ and ‘judgement’ are ‘old spellings’. For British people (like me) they are simply correct spellings! As a nation we have steadfastly resisted the descent into simplicity of spelling undertaken by our American cousins! We still wish each other Good Night, not ‘Good Nite’.

    One of my favourite (not favorite) pastimes is to criticise (not criticize) the way that Americans have been manoeuvred (not maneuvered) into using English. I also take some (perhaps small-minded) delight in pointing out where English came from! Oh well – you say pajamas and and I say pyjamas. Good Nite!

  10. Thanks for addressing the “compliment” vs. “complement” issue. As an economics teacher, I run into this a lot. I like the mnemonic that complement means to complete. In Economics, cars and gas are considered complementary because a car is not complete without gas and vice versa.

  11. Thank you very much! I really found the article and the comments are very helpful. I’ve got the answer for the irregular use of “compliment”.

  12. To the person calling themselves, “This Site Sucks,” Wiktionary says “complir is from the Latin root *complire < complēre, present active infinitive of compleō." Someone made a typo and put 'u' where an 'o' should have been. Get over yourself. It's been two years now, so my guess would be you won't see this comment. Too bad.

  13. Why can’t we leave language as a mean to communicate your ideas or thoughts. What’s in a spelling or grammar as long as you are able to present your self effectively.

  14. Hi Amit. Is it important, when speaking or writing, that we be clearly understood. Errors such as this can lead to misunderstanding, sometimes minor and sometimes not. This is even more important in written word, as we may not have the opportunity to clarify for the reader.

    The reason I ended up in this conversation is that I recently received an email informing me that I would be receiving complementary tickets to an event. I replied asking what the tickets were complementing (perhaps there was also a nice bottle of wine on route by post).

    The sender, a college professor, replied and informed me that I had mistaken “complementary” for “complimentary”, which she informed me meant “free” for the former, while the latter would describe someone who was speaking kindly of me.

    I did not reply with a correction, as I would prefer to be compimentary of this educator, however I considered sending her a grammar manual, both to compliment her for being so kind to send me the tickets, and to complement her knowledge of language.

    With regards,

    Your neighbour from the north.

  15. I just did that mistake and it was pointed out to me and so I had to research about Complement and Compliment! Glad there are people who care about proper grammar! Regards

  16. This is what helps me to remember what’s what:
    Compliment- pli, the “i” as in saying something “nice” the i in nice is how I remember which pli or ple to use.

    Complement-ple, complete. Example: Salt complements pepper. We complement each other as in You complete me.:)

  17. I now am clearer about “compliment” v. “complement.” The person who wrote about “every day,” however, started two sentences with conjunctions, which recently has been popularized but still is wrong. The split between “be” and “understood” in a more recent post also is incorrect.

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