supplement

1 of 3

noun (1)

sup·​ple·​ment ˈsə-plə-mənt 

1

a

: something that completes or makes an addition

b

: dietary supplement

2

: a part added to or issued as a continuation of a book or periodical to correct errors or make additions

3

: an angle or arc that when added to a given angle or arc equals 180°

supplement

2 of 3

verb

sup·​ple·​ment ˈsə-plə-ˌment 

supplemented; supplementing; supplements

transitive verb

: to add or serve as a supplement to

does odd jobs to supplement his income

supplementation

ˌsə-plə-ˌmen-ˈtā-shən 

-mən-

noun

supplementer

ˈsə-plə-ˌmen-tər 

noun

supplementation

3 of 3

noun (2)

sup·​ple·​men·​ta·​tion ˌsəplə(ˌ)men‧ˈtāshən 

-mən‧-

plural -s

: the act or process or an instance of supplementing

dietary supplementation

supplementation of state unemployment benefits

—R. A. Lester

Synonyms of supplement

Noun (1)

• increase
• boost
• addition
• gain

Examples of supplement in a Sentence

Noun (1)

the supplement to the encyclopedia

First-class accommodation is available for a supplement.

Verb

She began supplementing her diet with vitamins.

Recent Examples on the Web

Noun

What to know about the supplements people often use to help with falling asleep, jet lag, muscle tension and more. — Lindsey Bever, Washington Post, 2 Aug. 2026

One of Vogue’s favorite vitamin C supplements, Thorne’s Vitamin C With Flavonoids supports skin health and the vascular system, while Cymbiotika’s Liposomal Vitamin C, which also supports collagen production, has a refreshing, citrus-vanilla flavor. — Jenny Berg, Vogue, 31 July 2026

Verb

Local governments across the metro contribute funding to its operations, supplemented by grants and, recently, rider fares. — Ilana Arougheti july 30, Kansas City Star, 30 July 2026

Chief Judge Joan Ericksen, a federal judge from Minnesota, initially ordered the DOJ to supplement its legal arguments before later finding probable cause to allow the case to proceed. — Kaelan Deese, The Washington Examiner, 30 July 2026

Word History

Etymology

Noun (1)

Middle English, borrowed from Anglo-French & Latin; Anglo-French, borrowed from Latin supplēmentum "something added to supply a deficiency or make up a whole, reinforcement," from supplēre "to fill up, complete, raise to its full complement" + -mentum -ment — more at supply entry 2

Verb and Noun (2)

derivative of supplement entry 1

First Known Use

Noun (1)

14th century, in the meaning defined at sense 1a

Verb

1659, in the meaning defined above

Phrases Containing supplement

• colour supplement
• dietary supplement

Kids Definition

supplement

1 of 2 noun

sup·​ple·​ment ˈsəp-lə-mənt 

1

: something that supplies what is needed or makes an addition

vitamin pills used as dietary supplements

2

: an arc or angle that when added to a given arc or angle equals 180 degrees

supplemental

ˌsəp-lə-ˈment-ᵊl

adjective

supplement

2 of 2 verb

sup·​ple·​ment ˈsəp-lə-ˌment 

: to add to

supplement their incomes by doing odd jobs

supplementation

ˌsəp-lə-ˌmen-ˈtā-shən 

-mən-

noun

Medical Definition

supplement

1 of 2 noun

sup·​ple·​ment ˈsəp-lə-mənt 

1

: something that completes or makes an addition

2

: dietary supplement

supplement

2 of 2 transitive verb

sup·​ple·​ment ˈsəp-lə-ˌment 

: to add a supplement to : serve as a supplement for

utilizes … surgery to supplement the traditional treatment

—Therapeutic Notes

supplementation

ˌsəp-lə-ˌmen-ˈtā-shən, -mən- 

noun