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Complement vs. Compliment: What’s the Difference?

Updated on August 12, 2022Grammar
A cartoon of a triangle where each corner has a face and geometric markings; a play on the words "compliment" and "complement." The two acute angles compliment each other ("you're cute!" "you're terrific!") while the right angle quips, "get a square, you two!"

Here’s a tip: A complement is related to completion, while a compliment relates to flattering words or acts.

Everybody loves a compliment. Or is it a complement they love? If there is a published list of commonly confused words, complement and compliment are almost certain to appear. However, these two terms don’t have to be on your personal list of befuddling vocabulary! Here’s the breakdown.

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Complement definition

Complement and compliment used to share some meanings, because they derive from the same Latin root word. Complement used to mean “to compliment,” but that meaning is obsolete. Compliment has an archaic meaning also; it used to mean “gift.”

How can you define complement? If you think complement looks a little like the word complete, that can help you to remember some of its most useful meanings. A complement is something that completes or perfects.

Her dress perfectly complements the shade of her eyes.

They make a great couple; their personalities are a perfect complement to one another.

Here’s an example:

In grammar, it’s a word or group of words that completes a grammatical construction: A complement is part of the predicate of a sentence and describes either the subject of the sentence or the direct object. If it modifies the subject, it is called a subject complement. If it modifies or renames the direct object and follows it, it is called an object complement.


In science, the complement system refers to proteins that circulate in your blood. The name of the system derives from its function. Specific proteins match specific antibodies. In other words, the proteins complement the antibodies. Here is a brief explanation from

The complement system is a set of over 20 different protein molecules always found in the blood. . . . With an infection, this system of molecules is activated, leading to a sequence of events on the surface of the pathogen that helps destroy the pathogen and eliminate the infection.

Complements also appear in mathematics. A complement is an amount added to something to complete it. In geometry, it’s the quantity that an angle or an arc is short of ninety degrees.

Here are some examples from math websites:

If our universal set is the states of the United States, then a possible subset is the set of the New England states . . . {Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont}. The complement of A would then be the set containing all of the other states that are not part of New England.


When two angles add to 90°, we say they “complement” each other. Complementary comes from Latin completum meaning “completed” because the right angle is thought of as being a complete angle.


In economics, the definition of complementary goods is interesting. These items have little or no value on their own, but they add value to other items. Investopedia gives hot dog buns as a real world example of this concept. Most people don’t use hot dog buns alone, but they love them filled with hot dogs and all their favorite fixings.

Complement as a verb

As a verb, what does complement mean? In general, it means “to complete, to provide something lacking, or form a complement to.” Here’s one example of complement in a sentence from the web:

“One technology doesn’t replace another, it complements. Books are no more threatened by Kindle than stairs by elevators.”

—Stephen Fry

Complement synonyms

  • Addition is a synonym when the amount added completes a whole.
  • A companion is a mate or a match. Some Bible versions use “a helper as [the first man’s] complement” to describe the first woman.
  • Completion is the state of being whole, fulfilled, or concluded.
  • A counterpart is one of two parts that complement or complete one another. In the context of relationships, it often refers to a fitting match.
  • Enhancements intensify or raise the value of something. This definition most closely corresponds to a complement good or service.
  • Makeweights complete a desired weight on a scale. If you had eight pounds of a substance and you wanted to have ten pounds in total, the two pounds that you add to reach the correct weight are your makeweight.

Compliment Definition

How do you define compliment? It’s is an expression of praise, commendation, respect, or regard. It can be a formal act or as simple as a courteous greeting or wishing someone well. Notice these examples:

“To be trusted is a greater compliment than being loved.”

—George MacDonald

“I take no leave of you, Miss Bennet. I send no compliments to your mother. You deserve no such attention. I am most seriously displeased.”

—Pride and Prejudice by Jane Austen

Compliment as a verb

The verb compliment means to praise, congratulate, or say something admiring to someone. It can also include showing kindness. Compliments may come in the form of a friendly gesture or a gift.

“Compliment people. Magnify their strengths, not their weaknesses.”

—Joyce Meyer

Praise is not the only definition of compliment. Merriam-Webster Learner’s Dictionary helps demonstrate how native speakers might use the phrase “compliments of” with some examples. In the first example below, the phrase identifies the provider of something given at no charge. The second example uses the phrase sarcastically to refer to the source of something unwanted.

We were served free drinks, compliments of the casino.

I woke up with a stiff neck, compliments of that uncomfortable mattress in their guest room.

Compliment synonyms

  • Adulation is an excessive form of flattery related linguistically to a Latin word for the way dogs fawn over their masters.
  • Flattery refers to favorable comments about a person, but it can also refer to insincere remarks.
  • Homage is respect or honor paid to a person, sometimes in a public or formal setting.
  • Praise is the act of expressing favor or admiration. Singing someone’s praises is expressing high approval.

Compliment vs. complement: Tricks to remember the difference

How can you differentiate between compliment and complement? One trick is to give yourself a compliment:

Are you smart, creative, or compassionate? Tell yourself so, and then acknowledge:

I love how smart I am!

When you acknowledge your compliment, you will recall that the letter I is the difference between compliment and complement. These terms are homophones, words that sound alike but have different definitions and spellings. This trick will also help you decide how to spell each word correctly in the proper context. If you are not a fan of tooting your own horn, you could associate the I with insult. An insult is the opposite of a compliment. To remember complement, think of the word enhance when you look at the e. Enhancement is a synonym of complement.

Complimentary vs. complementary

What about the related words complimentary and complementary? Both of these words function as adjectives. Complimentary means “expressing a compliment” or “favorable.” It can also mean “free” in reference to items or services provided as a courtesy. Complementary refers to enhancing or emphasizing the qualities of another person or thing.

In medicine, complementary refers to alternative medicine or additional treatment that is administered alongside traditional medicine.

 Do you love nice compliments? If you are ready to remove compliment and complement from your personal list of confusing words, you deserve one! Good job on mastering two easily confused words!

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