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.  

Synonym Usage

See appendix. See complement.

Other Word Forms

Derived Forms

• well-supplemented
  adjective
• supplementer
  noun
• supplementation
  noun
• unsupplemented
  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”; see 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

This month, Brown and her colleagues published two new studies in The Astrophysical Journal and The Astrophysical Journal Supplement Series.

From Science Daily • Feb. 24, 2026

Mr. Forbes’s work has appeared in the Times Literary Supplement and elsewhere.

From The Wall Street Journal • Jan. 2, 2026

In December, he gave a presentation to the agency’s Office of Dietary Supplement Program, claiming that there is “deceptive marketing of dietary supplements and functional foods containing mycelium fermented grain and labeled as ‘mushroom.’”

From Los Angeles Times • Jun. 18, 2025

Supplements are regulated for safety but not efficacy by the 1994 Dietary Supplement Health and Education Act, which is enforced by the U.S.

From Salon • May 18, 2025

It got as far as the Supplement volume of the new OED, which is something, but not enough to assure survival.

From "The Lives of a Cell" by Lewis Thomas

Related Words

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