complementary

American  

[kom-pluh-men-tuh-ree, -tree] / ˌkɒm pləˈmɛn tə ri, -tri /

adjective

1. forming a complement; completing.

2. complementing each other.

---

noun

• complementaries
  plural

1. complementary color.

complementary British  

/ 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

---

Usage

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.

Other Word Forms

Derived Forms

• complementariness
  noun
• uncomplementary
  adjective
• complementarily
  adverb

Inflected Forms

Nouns

• complementaries
  plural

Etymology

Origin of complementary

First recorded in 1590–1600; complement + -ary

Explanation

If something is complementary, then it somehow completes or enhances the qualities of something else. If your beautiful voice is completely complementary to your brother's song writing skills, you should form a family band! You’ve probably heard of “complementary colors,” colors that are opposite in hue on the color wheel but actually go well together. When combined, they make a harmonious palette. People’s personalities can also be complementary, as can certain food pairings. But be careful not to confuse this adjective with the closely spelled complimentary, which means “supplied free of charge.”

Example Sentences

See Examples For:

complementary complementaries

Wilkinson said the two parties were looking at areas "where we have complementary capabilities and needs" and that are "strategically important" to "ensure our sovereignty", such as energy, artificial intelligence and critical minerals.

From Barron's ● Sep. 16, 2026

Speaking to reporters at the Toronto International Film Festival, Carney denied Canada was seeking formal membership, saying: "We share the same values. We have the same priorities, and we have very complementary strengths."

From BBC ● Sep. 14, 2026

In light of the migraine-study results, Ipsen could look for complementary deals, using Dysport as an anchor product around which to build a franchise, Loew said.

From The Wall Street Journal ● Sep. 11, 2026

It needs to answer the question: How can a team expect to be complimented if it can’t play complementary football?

From Los Angeles Times ● Aug. 30, 2026

The two eras were not so much in opposition as they were complementary developments, indicative of a single fact: Students at the new middle-class campus lacked deep appreciation of their social advantages.

From "Hunger of Memory" by Richard Rodriguez

But just as much as complementaries, van Gogh loved using colors that are adjacent on the color wheel.

From Washington Post ● Mar. 12, 2019

This novel about young Ged’s education in both magic and self-understanding relies throughout on Taoist notions of complementaries — the balance between light and dark, speech and silence, self and shadow.

From Washington Post ● Oct. 3, 2016

There are pairs of so-called complementaries which make a very crude, harsh, even painful impression.

From The Psychology of Beauty by Ethel Dench Puffer Howes

The great difficulty lies in discovering the conditions governing these groups of numbers, the pairing of the complementaries in the squares of four and the formation of the diagonals.

From Amusements in Mathematics by Henry Ernest Dudeney

The placing of complementaries so as to increase contrast is another way of adding to the brilliancy of light.

From The Painter in Oil A complete treatise on the principles and technique necessary to the painting of pictures in oil colors by Daniel Burleigh Parkhurst

Related Words

• integral
• interdependent
• reciprocal