complementary

[ kom-pluh-men-tuh-ree, -tree ]

adjective

1. forming a complement; completing.
2. complementing each other.

noun

, plural com·ple·men·ta·ries.

1. complementary color ( def 1 ).

complementary

/ ˌkɒmplɪˈmɛntərɪ; -trɪ /

adjective

1. acting as or forming a complement; completing
2. forming a satisfactory or balanced whole
3. forming a mathematical complement

   sine and cosine are complementary functions

4. maths logic (of a pair of sets, etc) mutually exclusive and exhaustive, each being the complement of the other
5. (of genes) producing an effect in association with other genes
6. involving or using the treatments and techniques of complementary medicine

Derived Forms

• ˌcompleˈmentarily, adverb
• ˌcompleˈmentariness, noun

Other Words From

• comple·menta·ri·ness noun
• uncom·ple·menta·ry adjective

Word History and Origins

Origin of complementary¹

First recorded in 1590–1600; complement + -ary

Example Sentences

Both programs also offered complementary therapies such as psychoeducation, anger management, medication management and art therapy, among others.

From Science Daily

"By combining their complementary expertise, the two companies plan to reduce development costs and scale new technologies more quickly," the two companies said in a statement.

From BBC

“There wasn’t any sort of semblance of complementary football,” said McVay.

From Los Angeles Times

The cousins’ complementary natures may have bonded them in their youth, and a genuine and abiding love clearly remains.

From Los Angeles Times

In New Zealand, safeguards are provided by an existing act of parliament and a separate, complementary policy that recognises the importance of national, regional and local surf spots.

From BBC

Related Words

• integral
• interdependent
• reciprocal

Complementary Vs. Complimentary

What’s the difference between complementary and complimentary?

Complementary is an adjective used to describe something that complements something else—goes along with it and serves to make it better or complete it (as in complementary colors). Complimentary is an adjective that can describe something intended to be a compliment—a comment that expresses praise or admiration of someone (as in a complimentary remark). It can also be used to mean that something is given for free, as in I hope we get complimentary snacks on this flight.

Since the primary senses of both words are generally used in positive contexts, it can be easy to confuse them.

The easiest way to remember the difference is that complementary often involves something that completes something else, and complete also starts with c-o-m-p-l-e. On the other hand, you can remember that complimentary is spelled with an i because compliments are something that I like to get (and give). Nice shirt, by the way.

Here’s an example of complementary and complimentary used correctly in the same sentence.

Example: Sometimes, when the chef overhears complimentary feedback about a dish, she sends out a complimentary bottle of wine—one that’s complementary to the rest of the meal, of course.

Want to learn more? Read about the difference between compliment and complement.

Quiz yourself on complementary vs. complimentary!

Should complementary or complimentary be used in the following sentence?

My comment was meant to be _____—I really do like your shoes!