Quick answer: Complementary means completing or going well together with something else, forming a whole: complementary colours; complementary skills. Complimentary means expressing praise, or given free of charge: a complimentary remark; a complimentary breakfast. Memory trick: complEmentary is about complEting something; complImentary is about a complIment or something free. For a fuller definition, see the Cambridge Dictionary entry for ‘complementary’.
Comparison Table
| Word | Part of Speech | Meaning | Example |
|---|---|---|---|
| complementary | adjective | completing or going well together with something else, forming a whole | Orange and blue are complementary colours. |
| complimentary | adjective | expressing praise or admiration; or given free of charge | The hotel offers a complimentary breakfast. |
Using Complementary
Complementary describes two or more things that go together well, each enhancing or completing the other, or combining to form a complete whole. It comes from the noun complement (something that completes).
Red and green are complementary colours on the colour wheel.
The two managers have complementary skills — one is creative, the other organised.
Acupuncture is often used as a complementary therapy alongside conventional medicine.
The wine and the cheese were perfectly complementary.
Their personalities are complementary, which makes them a strong team.
Common Collocations with Complementary
- complementary colours
- complementary skills / complementary strengths
- complementary medicine / complementary therapy
- complementary angles (in geometry — angles that add up to 90 degrees)
Using Complimentary
Complimentary has two related meanings: (1) expressing praise or admiration, and (2) given free of charge, as a courtesy. Both senses come from the noun compliment (an expression of praise, or a courteous gift).
She made a complimentary remark about his presentation.
The reviews of the restaurant were largely complimentary.
Guests receive a complimentary glass of champagne on arrival.
The airline offered complimentary Wi-Fi to business-class passengers.
We provide a complimentary consultation before you commit to any service.
Common Collocations with Complimentary
- complimentary breakfast / complimentary drink
- complimentary tickets / complimentary copy
- complimentary remark / complimentary review
- complimentary consultation / complimentary upgrade
This pair sits alongside the related nouns and verbs complement (to complete) and compliment (to praise), which are covered on our complement vs compliment page — this article focuses specifically on the adjective forms, complementary and complimentary. For learners who want a deeper look at how adjectives function and combine in English, see our guide to adjectives.
Memory Trick
ComplEmentary contains the same root as complEte and complEment — things that complEte each other. ComplImentary contains the same root as complIment (praise) — and also happens to describe things given for free, like a gift. If a hotel gives you something for free, it is complIment-ary, like a compliment from the hotel to you.
Common Mistakes
✗ The two colours are complimentary.
✓ The two colours are complementary.
✗ The hotel offers a complementary breakfast.
✓ The hotel offers a complimentary breakfast.
✗ She was very complementary about the new design.
✓ She was very complimentary about the new design.
✗ They make a great team because they have complimentary skills.
✓ They make a great team because they have complementary skills.
Quick Check: Complementary or Complimentary?
Four questions — choose the correct word for each sentence.
1. “The hotel gave us a ___ upgrade to a suite.”
2. “Their two skill sets are ___, which makes the project work.”
3. “He was very ___ about my cooking.”
4. “Blue and orange are ___ colours.”
Frequently Asked Questions
What is the difference between complementary and complimentary?
Complementary describes things that go well together and complete a whole, such as complementary colours or complementary skills. Complimentary describes praise or admiration ("a complimentary remark") or something given free of charge ("a complimentary drink"). The two adjectives are pronounced almost identically but come from different root words — complement (to complete) and compliment (praise) — and are never interchangeable.
Is a free hotel breakfast "complementary" or "complimentary"?
It is "complimentary breakfast," using the I spelling, because it means the breakfast is given free of charge as a courtesy from the hotel. "Complementary breakfast" would be a spelling mistake in this context. Remember: anything provided for free — drinks, Wi-Fi, upgrades, tickets — uses complimentary, the same root as "compliment," a gift of goodwill.
How can I remember complementary vs complimentary?
Complementary shares its spelling with "complete" — both contain an E — and describes things that complete each other, like complementary colours. Complimentary shares its spelling with "compliment" — both contain an I — and describes praise or free items, like a compliment from a business to its customers. Linking each word to its matching root (complete/complement vs compliment/compliment) is the most reliable memory trick.
What are complementary colours?
Complementary colours are pairs of colours positioned opposite each other on the colour wheel, such as red and green, or blue and orange. When placed together, they create strong visual contrast and make each other appear more vibrant. This is a common term in art, design, and photography courses, and always uses the E spelling because the colours "complete" or balance each other visually.
What does "complementary medicine" mean?
Complementary medicine refers to treatments, such as acupuncture, massage, or herbal remedies, that are used alongside conventional medical treatment rather than instead of it. The term uses the E spelling because these therapies are meant to complement, or complete, standard medical care. This differs from "alternative medicine," which is used instead of conventional treatment.
Can "complimentary" describe a person's tone or attitude?
Yes. Complimentary describes speech or writing that expresses praise or approval: "The critics were complimentary about her debut novel"; "He made a complimentary comment about my presentation." This use focuses purely on praise, not on anything being free, and shares its root directly with the noun "compliment."
Are "complementary" and "supplementary" related?
They are related in meaning but not interchangeable. Complementary implies two things completing each other as an ideal pair — like complementary skills in a team. Supplementary means additional or extra, without necessarily implying a perfect match — like supplementary reading material for a course. Complementary suggests balance and completeness; supplementary simply suggests addition.
What are complementary angles in geometry?
In geometry, complementary angles are two angles whose measures add up to exactly 90 degrees. For example, a 30-degree angle and a 60-degree angle are complementary because together they complete a right angle. This mathematical term always uses the E spelling, following the same logic as complementary colours — the two parts complete a whole.
Is "complimentary" always about something free?
No — complimentary has two separate senses. It can mean expressing praise ("a complimentary review") or given free of charge ("a complimentary ticket"). Context usually makes the intended meaning clear: reviews and remarks are complimentary in the sense of praise, while drinks, samples, and upgrades are complimentary in the sense of being free.
Why are complementary and complimentary so often confused?
The two words are pronounced almost identically in natural speech, and both derive from Latin roots that are historically related (complere, "to complete," and complementum). Because spell-checkers often accept either word as valid, the error frequently slips through in marketing materials, hotel signage, and business writing, making it one of the more persistent confusable pairs in professional English.