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

In this new landscape TCU would have the same money to spend on its roster as Ohio State or Alabama, but college football’s history has shown that if there is a loophole to be finessed then a college booster or coach will find it. —Fort Worth Star-Telegram, 11 July 2025

College sports fandom has long been led by old-fashioned booster clubs and message boards that popped up 20 years ago. —Chris Vannini, New York Times, 11 July 2025

Waymo boosters regularly argue on the site that the company is years ahead of Tesla in experience: Waymo had paying customers in its first market, Phoenix, while still using safety drivers in December 2018 — six and a half years ago. —David Ingram, NBC news, 5 July 2025

While Venus is in Taurus, keep a cheerleader or two around as confidence boosters! —Usa Today, USA Today, 4 July 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