supplement

American  

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

noun

• supplements
  plural

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)

• supplements,
  present (3rd person singular)
• supplemented,
  past participle,  past
• supplementing
  present participle

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

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

Inflected Forms

Nouns

• supplements
  plural

Participles

• supplementing
  present
• supplemented
  past

Conjugated Forms

Present

• supplement
  simple
• supplements
  simple
• have supplemented
  perfect
• has supplemented
  perfect
• am supplementing
  progressive
• are supplementing
  progressive
• is supplementing
  progressive
• have been supplementing
  perfect progressive
• has been supplementing
  perfect progressive

Past

• supplemented
  simple
• had supplemented
  perfect
• was supplementing
  progressive
• were supplementing
  progressive
• had been supplementing
  perfect progressive

Future

• will supplement
  simple
• will have supplemented
  perfect
• will be supplementing
  progressive
• will have been supplementing
  perfect progressive

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

See Examples For:

supplement supplements supplemented supplementing

The company has continued hiring engineers to supplement the additional productivity it has gained from AI tools, he added, and invests over $150 million each year in research and development.

From The Wall Street Journal ● Oct. 5, 2026

I have Medicare, but I’ve kept the employer coverage as a supplement because I’m afraid of gaps.

From MarketWatch ● Oct. 2, 2026

Medical staff agreed to give Ann an intravenous supplement of vitamin B6, which appeared to stop her seizures.

From BBC ● Oct. 1, 2026

The premiums vary, but the national average for a 65-year-old was recently $217 a month for a Medicare supplement, according to the Medicare Payment Advisory Commission.

From The Wall Street Journal ● Oct. 1, 2026

My mom and I had pooled our resources to supplement my winter wardrobe, but it was still scanty.

From "Twilight" by Stephenie Meyer

Amid the 2026 Ebola outbreak in the Democratic Republic of Congo, videos of a doctor recommending Vitamin D3 and zinc spread from accounts selling supplements, despite these being unable to treat the disease.

From Barron's ● Oct. 8, 2026

There were problems with spending on suspicious health supplements.

From MarketWatch ● Oct. 6, 2026

Max Longman, 32, from Manchester, works in real estate and has been taking protein supplements for 10 years, originally to help him gain weight.

From BBC ● Sep. 23, 2026

Calcium and vitamin D supplements are widely taken to support bone health, especially by older adults.

From Science Daily ● Sep. 21, 2026

Bookshelves lined the far wall, filled with role-playing game supplements and back issues of Dragon magazine.

From "Ready Player One: A Novel" by Ernest Cline

The witches are thus visible manifestations of internal malevolent urges, and the 12 dancer witches who supplemented the large singing chorus of hags appeared throughout the evening—observing, slipping through walls, and egging the protagonists on.

From The Wall Street Journal ● Sep. 24, 2026

"I like to think we have aided scouts and recruitment teams, supplemented them with the tools, data, information to be able to make more informed decisions on a more consistent basis."

From BBC ● Sep. 23, 2026

Over the years, my mother and I have supplemented his income.

From MarketWatch ● Sep. 10, 2026

Tesla has long promised a profitable robotaxi business, powered primarily by the Cybercab and supplemented by self-driving Tesla Model Y vehicles.

From Los Angeles Times ● Sep. 4, 2026

Modern salaries, of course, are supplemented by the employer’s pension contributions and other charges, so they cannot be directly compared with seventeenth-century salaries.

From "The Invention of Science" by David Wootton

They also need to understand whether altering Menin or supplementing D-serine could produce unintended effects.

From Science Daily ● Sep. 18, 2026

The ratio was changed a bit—ground ops were supplementing the air war, not the other way around; but still the ground ops were necessary.

From Slate ● Jul. 30, 2026

Triple-feeding aims to increase production by breastfeeding the baby, followed by supplementing - usually by bottle - with expressed milk or formula, before pumping for 15 minutes.

From BBC ● Jun. 15, 2026

The Dodgers are supplementing where they can, picking up three pitchers cut by their former clubs.

From Los Angeles Times ● May 19, 2026

A contingent of German soldiers seemed to be supplementing the regular police force.

From "The Hiding Place" by Corrie ten Boom

Related Words

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