Quick answer
A complement completes something, or improves it by pairing well — the wine complements the fish. A supplement adds to something already sufficient — a supplement to a report, a vitamin supplement. Complement completes; supplement adds on.
The core difference
Both improve the thing they join. The difference is whether it was incomplete.
- complement — completes or perfectly accompanies: the colours complement each other.
- supplement — an addition to something already whole: a weekend supplement.
The spelling trap
Complement with an E completes; compliment with an I is praise. The mnemonic: complEment complEtes. That pair is a separate confusion and worth keeping distinct from this one.
The technical senses
In grammar, a complement completes the meaning of a verb. In geometry, complementary angles total 90 degrees. In immunology, the complement system is a set of proteins. All three use the completing sense.
Frequently asked questions
What is the difference between complement and compliment?
Complement with an E completes something; compliment with an I is an expression of praise.
Which word for a vitamin?
Supplement — it adds to a diet that is otherwise adequate.
How do I remember complement?
ComplEment complEtes. The E links them.
