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

Ukrainians also use Delta and complementary applications to improve situational awareness and protect their own troops.

From The Wall Street Journal ● Sep. 25, 2026

“It’s a way for them to to show a willingness to integrate within cities and to be more complementary rather than replacing,” Cornet said.

From Los Angeles Times ● Sep. 24, 2026

Neutron and X-ray imaging provide researchers with complementary ways to see inside materials.

From Science Daily ● Sep. 24, 2026

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

We suspected that we had not made this error, but our judgment conceivably might be biased by the biological advantages of complementary DNA molecules.

From "Double Helix" by James D. Watson

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

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

These primaries are red, green, and blue and it will be noted that they are the complementaries of the "subtractive" primaries.

From Artificial Light Its Influence upon Civilization by Matthew Luckiesh

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 Walter Crane

Related Words

• integral
• interdependent
• reciprocal