booster

noun

boost·​er ˈbü-stər 

: one that boosts: such as

a

: an enthusiastic supporter

b

: an auxiliary device for increasing force, power, pressure, or effectiveness

c

slang : shoplifter

d

: a radio-frequency amplifier for a radio or television receiving set

e

: the first stage of a multistage rocket providing thrust for the launching and the initial part of the flight

f

: a substance or dose used to renew or increase the effect of a drug or immunizing agent

especially : booster shot

Synonyms of booster

• proponent
• supporter
• advocate
• advocator
• exponent
• promoter

Examples of booster in a Sentence

These exercises are real metabolism boosters.

Music is my favorite mood booster.

A sincere compliment can be a true confidence booster.

The university has a number of wealthy boosters who contribute generously each year.

a new design for rocket boosters

Recent Examples on the Web

The city’s recreation department and community boosters will host two egg hunts, one for children ages 5-10 and one for ages 4 and under (with parents), followed by a bunny hop dance party. —Linda Zavoral, Mercury News, 27 Mar. 2026

Artemis 2 rocket creeps along toward launch pad NASA's Artemis 2 moon rocket, the second-ever Space Launch System booster, is slowly making progress along the 4-mile journey to its Florida pad at Launch Complex 39B at the Kennedy Space Center in Cape Canaveral, Florida. —Josh Dinner, Space.com, 27 Mar. 2026

Final Four runs because of an NCAA violations scandal involving booster Ed Martin. —Joseph Buczek, CBS News, 27 Mar. 2026

Many of his peers and former rivals have long since retired, burned out by the task of recruiting and coaching while also raising funds from boosters in order to build title-contending rosters. —Greg Rosenstein, NBC news, 26 Mar. 2026

Word History

First Known Use

1888, in the meaning defined above

Phrases Containing booster

• booster chair
• booster cushion
• booster dose
• booster seat
• booster shot

Rhymes for booster

• rooster

Kids Definition

booster

noun

boost·​er ˈbü-stər 

1

: one that boosts

2

: an enthusiastic supporter

3

: booster shot

4

: a device for strengthening radio or television signals

5

: the first stage of a multistage rocket providing force for the launching and the first part of the flight

Medical Definition

booster

noun

boost·​er ˈbü-stər 

: a substance or dose used to renew or increase the effect of a drug or immunizing agent: such as

a(1)

: booster shot

(2)

: booster dose

b

: synergist sense 1

a chemical acting as a booster to sulfa drugs