complement

American  

[kom-pluh-muhnt, kom-pluh-ment] / ˈkɒm plə mənt, ˈkɒm pləˌmɛnt /

noun

• complements
  plural

1. something that completes or makes perfect.

   A good wine is a complement to a good meal.

2. the quantity or amount that completes anything.

   We now have a full complement of packers.

3. either of two parts or things needed to complete the whole; counterpart.

4. full quantity or amount; complete allowance.

5. the full number of officers and crew required on a ship.

6. Grammar.

   1. a word or group of words that completes a grammatical construction in the predicate and that describes or is identified with the subject or object, as small in The house is small or president in They elected her president.

   2. any word or group of words used to complete a grammatical construction, especially in the predicate, including adverbials, as on the table in He put it on the table, infinitives, as to go in They are ready to go, and sometimes objects, as ball in He caught the ball.

7. Geometry. the quantity by which an angle or an arc falls short of 90° or a quarter of a circle.

8. Also called absolute complement. Mathematics. the set of all the elements of a universal set not included in a given set.

9. Music. the interval that completes an octave when added to a given interval.

10. Immunology.

    1. a system in vertebrate blood of 12 or more proteins that react in a cascade to a cell displaying immune complexes or foreign surfaces, acting in various combinations to coat the cell and promote phagocytosis, make holes in the cell wall, or enhance the inflammatory response.

    2. any of the proteins in the complement system, designated C1, C2, etc.

11. complementary color.

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verb (used with object)

• complements,
  present (3rd person singular)
• complemented,
  past participle,  past
• complementing
  present participle

1. to complete; form a complement to.

   This belt complements the dress better than that one.

2. Obsolete. to compliment.

verb (used without object)

• complements,
  present (3rd person singular)
• complemented,
  past participle,  past
• complementing
  present participle

1. Obsolete. to compliment.

complement British  

noun

1. a person or thing that completes something

2. one of two parts that make up a whole or complete each other

3. a complete amount, number, etc (often in the phrase full complement )

4. the officers and crew needed to man a ship

5. grammar

   1. a noun phrase that follows a copula or similar verb, as for example an idiot in the sentence He is an idiot

   2. a clause that serves as the subject or direct object of a verb or the direct object of a preposition, as for example that he would be early in the sentence I hoped that he would be early

6. maths the angle that when added to a specified angle produces a right angle

7. logic maths the class of all things, or of all members of a given universe of discourse, that are not members of a given set

8. music the inverted form of an interval that, when added to the interval, completes the octave

   the sixth is the complement of the third

9. immunol a group of proteins in the blood serum that, when activated by antibodies, causes destruction of alien cells, such as bacteria

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verb

1. (tr) to add to, make complete, or form a complement to

complement Scientific  

/ kŏm′plə-mənt /

1. A group of proteins in blood serum that interact systematically as part of the body's immune response to destroy disease-causing antigens, especially bacteria. Complement proteins interact with antibodies and other chemical substances to cause the disintegration of foreign cells and enhance other immune functions such as phagocytosis.

2. A complementary color.

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Usage

What’s the difference between complement and compliment? The word complement most commonly refers to something that goes along with something else and serves to make it better or complete it. It’s also commonly used as a verb meaning to serve as a complement in this way, as in That necklace really complements the rest of your outfit. A compliment is a comment intended to express praise or admiration of someone. Compliment is also commonly used as a verb meaning to give a compliment. Complement has many other specific meanings, but compliment is really only used to refer to a nice comment or the action of giving one. Since the primary senses of both words are generally used in positive contexts, it can be easy to confuse them. The adjective form of complement is complementary, as in complementary colors. The adjective form of compliment is complimentary, which can describe something intended to be a compliment, as in complimentary remark, or it can be used to mean that something is given for free, as in I hope we get complimentary snacks on this flight. The easiest way to remember the difference is that complement often means to complete, and complete also starts with c-o-m-p-l-e. On the other hand, compliment is spelled with an i, and compliments are something that I like to get (and give). Nice shirt, by the way. Here’s an example of complement and compliment used correctly in the same sentence. Example: The chef overheard the diners at one table complimenting the way the sauce complemented the fish, so she told the server to offer them a complimentary dessert. Want to learn more? Read the full breakdown of the difference between complement and compliment.

Commonly Confused

Complement and compliment, which are pronounced alike and originally shared some meanings, have become separate words with entirely different meanings. As a noun, complement means “something that completes or makes perfect”: The rare old brandy was a perfect complement to the delicious meal. As a verb, complement means “to complete”: A bright scarf complements a dark suit. The noun compliment means “an expression of praise, commendation, or admiration”: The members paid her the compliment of a standing ovation. The verb compliment means “to pay a compliment to”: Everyone complimented him after the recital.

See compliment

Synonym Usage

Complement, supplement both mean to make additions to something. To complement is to provide something felt to be lacking or needed; it is often applied to putting together two things, each of which supplies what is lacking in the other, to make a complete whole: Two statements from different points of view may complement each other. To supplement is merely to add to: Some additional remarks may supplement his address.

Other Word Forms

Derived Forms

• complementer
  noun

Inflected Forms

Nouns

• complements
  plural

Participles

• complementing
  present
• complemented
  past

Conjugated Forms

Present

• complement
  simple
• complements
  simple
• have complemented
  perfect
• has complemented
  perfect
• am complementing
  progressive
• are complementing
  progressive
• is complementing
  progressive
• have been complementing
  perfect progressive
• has been complementing
  perfect progressive

Past

• complemented
  simple
• had complemented
  perfect
• was complementing
  progressive
• were complementing
  progressive
• had been complementing
  perfect progressive

Future

• will complement
  simple
• will have complemented
  perfect
• will be complementing
  progressive
• will have been complementing
  perfect progressive

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Etymology

Origin of complement

First recorded in 1350–1400; Middle English, from Latin complēmentum “something that completes,” equivalent to complē(re) “to fill, fill up” + -mentum noun suffix; see origin at complete, -ment

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Explanation

A complement is something that makes up a satisfying whole with something else. Those shiny red shoes you just bought complement your shiny red purse. Complement comes from the Latin complementum, "something that fills up or completes." Complement keeps both the e and the meaning. It's also a verb; if you and your partner complement each other, you make a perfect pair. Something that complements completes or adds a little something.

Example Sentences

See Examples For:

complement complements complemented complementing

Every show, she picks her clothes to complement what she anticipates her guest will be wearing.

From The Wall Street Journal ● Oct. 28, 2026

Within fulfillment, AI also works to complement broader operational changes.

From MarketWatch ● Oct. 28, 2026

Such payments should complement, not replace, unemployment insurance and retraining programs, she said.

From Barron's ● Oct. 26, 2026

She has made more substitutions than any other manager too, including using her full complement of five in all but one match.

From BBC ● Oct. 24, 2026

The company was right not to revise it to Think Differently: the verb think can take an adjectival complement which refers to the nature of the thoughts being entertained.

From "The Sense of Style" by Steven Pinker

"This complements changes that we carried out to our immigration hall recently to help improve the flow of arriving passengers through the area."

From BBC ● Oct. 6, 2026

“The strength on one side complements a gap on the other side,” Seibly said.

From The Wall Street Journal ● Sep. 7, 2026

Each one has her singular presence — Trachtenberg plucky and inspiring; Panettiere charming and bold — but together, they’re beautiful complements.

From Salon ● Aug. 18, 2026

Layered images hint at the underlying complexity while St. Vincent’s “Slow Disco” complements the meditative rhythm.

From Los Angeles Times ● Aug. 12, 2026

Most verbs that take subjectless complements, such as try in Alice tried to calm down, are governed by an ironclad rule that forces the overt subject to be identical to the missing subject.

From "The Sense of Style" by Steven Pinker

Owen in those days, even after his initial hamstring struggles, was explosive, electric - searing pace and acceleration complemented by the most ruthless of finishes.

From BBC ● Oct. 27, 2026

“The main level features a spectacular primary suite, complemented by an upper-level second primary suite and four additional bedroom suites,” added the listing.

From MarketWatch ● Sep. 24, 2026

Neutron imaging allowed the team to confirm earlier observations, examine large bones including Scotty's rib without damaging them, and obtain additional image contrast that complemented the information gathered through other methods.

From Science Daily ● Sep. 24, 2026

It complemented his fragmented musical architecture, just as the blocked passions of the film’s characters are captured in his unresolved harmonies.

From The Wall Street Journal ● Sep. 4, 2026

His eyes were big and they complemented his full cheekbones, which looked as if he had something in his mouth.

From "A Long Way Gone: Memoirs of a Boy Soldier" by Ishmael Beah

Elsewhere, a custom bar creates a dedicated setting for hosting guests, complementing the residence’s spacious living and dining areas.

From MarketWatch ● Oct. 29, 2026

That combination raises the possibility of developing treatments that change how the body handles energy, potentially complementing medications that primarily work by reducing appetite.

From Science Daily ● Oct. 24, 2026

The low-band portfolio gives SpaceX a coverage layer with stronger in-building propagation, complementing the mid-band spectrum it’s acquiring from EchoStar, the analysts say.

From The Wall Street Journal ● Oct. 9, 2026

If L7 was a statement, Finch was its punctuation, her crayon-bright hair complementing a radiant humanity.

From Salon ● Jul. 21, 2026

Outdoors was the end of something, an irrevocable, physical fact, defining and complementing our metaphysical condition.

From "The Bluest Eye" by Toni Morrison

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