supplement

American  

[suhp-luh-muhnt, suhp-luh-ment] / ˈsʌp lə mənt, ˈsʌp ləˌmɛnt /

noun

1. something added to complete a thing, supply a deficiency, or reinforce or extend a whole.

2. a part added to a book, document, etc., to supply additional or later information, correct errors, or the like.

   Synonyms:

   postscript, epilogue, addendum

3. a part, usually of special character, issued as an additional feature of a newspaper or other periodical.

4. Geometry. the quantity by which an angle or an arc falls short of 180° or a semicircle.

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verb (used with object)

1. to complete, add to, or extend by a supplement.

2. to form a supplement or addition to.

3. to supply (a deficiency).

supplement British  

noun

1. an addition designed to complete, make up for a deficiency, etc

2. a section appended to a publication to supply further information, correct errors, etc

3. a magazine or section inserted into a newspaper or periodical, such as one with colour photographs issued every week

4. geometry

   1. either of a pair of angles whose sum is 180°

   2. Abbreviation: sup.   supp.  an arc of a circle that when added to another arc forms a semicircle

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verb

1. (tr) to provide a supplement to, esp in order to remedy a deficiency

Usage

What does supplement mean? A supplement is an addition to something that completes it or makes up for a shortcoming, as in He takes vitamin supplements to make up for his vitamin C deficiency. A supplement is also an addition to a book that provides important information or corrects errors. In this sense, supplement can be confused with the words appendix and index. An appendix gives additional information, such as charts and graphs, but the book or document would be considered complete without it. An index is an alphabetical list of names or topics with page numbers that helps you find something specific in the book, such as all the references to John Wilkes Booth in a biography of Abraham Lincoln. As a verb, supplement means to add to something, as in Tameka sold paintings to supplement her income. In this sense, supplement can be confused with the word complement. Both words mean to add something, but to complement means to add something to make up for a missing piece or element, while to supplement is to add extra information. Example: The company built a new roller coaster to supplement its original roller coaster, which always has a long line.  

Related Words

See appendix. See complement.

Other Word Forms

• supplementation noun
• supplementer noun
• unsupplemented adjective
• well-supplemented adjective

Etymology

Origin of supplement

First recorded in 1350–1400; Middle English, from Latin supplēmentum “that by which anything is made full,” equivalent to sup- sup- + plē- (stem of plēre “to fill”; full ¹ ) + -mentum -ment

Explanation

A supplement is something added to something else. Nutritional supplements add vitamins and minerals to the ones already included in the food you eat. If a zombie army wants to increase its ranks but is running out of bodies, it might supplement its troops with mummies. If the zombies put out their manifesto and then realize they left out an important point, they might supplement the manifesto with a press release. That press release could also be referred to as a supplement.

Example Sentences

The subscription model was created to supplement the expenses that ad revenue wasn’t covering.

From Los Angeles Times • Apr. 10, 2026

In addition, an annual supplement of £440 should be paid on cars with a list price of more than £40,000, or £50,000 for EVs.

From BBC • Mar. 31, 2026

“The inclusion of a maiden resource for West Dome Underground and extensions at Main Dome Underground outline exciting high-grade additions which can serve as a supplement to the base load low-grade open pit,” says Hissey.

From The Wall Street Journal • Mar. 30, 2026

While most engage in the debate and perhaps take a supplement or two, others graduate to more extreme options—and further levels of involvement.

From Slate • Mar. 30, 2026

He rigged a block and tackle to supplement a dead tree limb that they were using as a lever.

From "Redwall" by Brian Jacques

Related Words

• augment
• build up
• buttress
• complement
• enhance
• enrich
• fill out
• fortify
• improve
• reinforce
• strengthen
• subsidize