complementary

American  

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

adjective

1. forming a complement; completing.

2. complementing each other.

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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

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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

On Thursday, it announced it will acquire HRL Laboratories, which brings in complementary research on the fundamental units of quantum computing, called qubits.

From The Wall Street Journal ● Jul. 23, 2026

Much like the twins, their abilities appear predicated on a complementary duality to assist their masters.

From Salon ● Jul. 18, 2026

The foundation believes that alternative and complementary solutions should be taken into account -- like recycling water, collecting rain water and "better management of tourist demand".

From Barron's ● Jul. 13, 2026

The bacterium appears to fight cancer through two complementary mechanisms.

From Science Daily ● Jul. 10, 2026

They made a perfectly complementary pair, Thorne a skillful salesman who hawked the securities transactions contrived by the introverted Alfred.

From "Big Science" by Michael Hiltzik

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

We have already shown how the complementaries of the spectrum colours can be found; the question is can we find the complementaries of pigments by the spectrum?

From Colour Measurement and Mixture by Abney, W. de W.

Harmony in colour may be said to consist—apart from the general acknowledgment of the law of complementaries, in giving quality to the raw pigments by gradation, by a certain admixture or infusion of other colours.

From Line and Form (1900) by Crane, Walter

Everything in nature is manifested to us by means of light and its complementaries, reflection and shadow.

From The Mind of the Artist Thoughts and Sayings of Painters and Sculptors on Their Art by Binyon, Cicely Margaret Powell

Related Words

• integral
• interdependent
• reciprocal