What does complement mean?
Complement refers to something that completes, rounds out, or enhances another thing, bringing it to a fuller or more satisfying whole. A good sauce may be the perfect complement to a dish, or two colleagues' skills may complement each other when combined. The word also carries precise technical senses: in grammar, a complement is a word or phrase required to complete a sentence's meaning, while in mathematics it denotes the set of elements excluded from a given set. It can additionally mean the full quota or number required, as in a ship's full complement of crew. As a verb, to complement something is to pair with it in a way that improves or completes it. Complement is best understood through its root sense of completion: unlike a supplement, which merely adds to fill a gap, a complement perfects what already exists. Its homophone 'compliment', meaning praise, shares the same Latin ancestry but has drifted into an entirely different domain of meaning.
A thing that completes or goes well with something else, enhancing or making perfect; also, the complete number or quantity required, or a technical term in grammar and mathematics denoting an element needed to complete a structure or the part of a set excluded from it.
"Her calm manner was the ideal complement to his restless energy."
In British English the plural is 'complements'; the word is neutral in register across all its senses.
To add to something in a way that enhances, improves, or completes it.
"The fresh herbs complement the richness of the cheese beautifully."
Usually used transitively; often appears in contexts describing harmonious pairing of flavours, colours, skills, or styles.
Standard regular plural; used when referring to multiple things that each complete or enhance something else.
"The menu offers a range of side dishes designed as complements to the main courses."
'Complement' and 'compliment' come from the same Latin root — one completes a thing, and the other once meant the fulfilment of courtesy — which is why even native speakers mix them up centuries later.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of complement
Complement derives from the Latin 'complementum', meaning 'that which fills up or completes', formed from 'complere' ('to fill up'), itself a combination of 'com-' ('with, together') and 'plere' ('to fill'). It entered English via French in the late Middle Ages, initially carrying senses related to completion and fulfilment. It shares this Latin root with 'complete', 'completion', and — somewhat surprisingly — 'compliment', which evolved through Italian and Spanish from the same notion of fulfilling one's obligations, including those of courtesy.
Related word forms
How complement is actually used
As a verb, 'complement' typically carries a positive connotation of harmonious pairing rather than mere addition. The stress pattern is identical for noun and verb (stress on the first syllable), unlike words such as 'record' where noun and verb differ in stress. In grammar and mathematics, 'complement' is a precise technical term with specialised meanings that differ from everyday usage.
Easily confused with complement
A 'compliment' is a flattering remark expressing praise or admiration, while a 'complement' is something that completes or enhances something else; note that both are pronounced identically.
A supplement adds something extra to make up for a deficiency, whereas a complement completes or perfects what is already there without implying anything is missing.