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

• 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

As for the Super Heavy booster, SpaceX lost contact with the lower-stage during its descent about six minutes after launch. —Eric Lagatta, USA Today, 9 Oct. 2025

Touchdown Club projects To meet and maintain Carroll’s lofty athletic standards, booster clubs needed to raise significant funds to complete upgrades and facility improvements. —Charles Baggarly october 9, Fort Worth Star-Telegram, 9 Oct. 2025

In the era of NIL, schools have to weigh their budget for sports as a way to keep from slipping into irrelevance, which could hurt donations from boosters and enrollment. —Jordan Sigler, MSNBC Newsweek, 8 Oct. 2025

For older kids, a booster of the tetanus and pertussis vaccine is typically required, as well as a vaccine for meningococcal disease. —David Higgins, The Conversation, 7 Oct. 2025

Word History

First Known Use

1888, in the meaning defined above

Phrases Containing booster

• 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