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

plural

complementaries

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

• complementarily adverb
• complementariness noun
• uncomplementary adjective

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

Together, these discoveries suggest that nutrients from both plant and animal sources may work in complementary ways to support the immune system.

From Science Daily • Apr. 10, 2026

“It’s relaxing and complementary to a doctor’s dry eye treatments — like medicated drops or in-office treatments — but it’s not a simple fix or cure all,” she said.

From Los Angeles Times • Apr. 6, 2026

Anne Marie, a beauty and complementary therapist with her own successful business, was at a pub in East Kilbride, South Lanarkshire, with her cousins on the night of the incident.

From BBC • Mar. 30, 2026

Instead, Haleon has lined up a host of products complementary to GLP-1 drugs, such a specific Centrum vitamin for those taking the medication.

From The Wall Street Journal • Mar. 13, 2026

Her lips were coated in a complementary coral gloss, and a bit of the color had strayed beyond the borders.

From "Interpreter of Maladies" by Jhumpa Lahiri

Related Words

• integral
• interdependent
• reciprocal