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

If the goal isn’t to replace jobs, frame it as a productivity booster, not a threat. —Apurva Wadodkar, Forbes.com, 27 June 2025

Starship's upper stage has exploded and/or crashed into the sea on eight of its nine of its test flights to date (on two launches, the company managed to return the vehicle's Super Heavy booster to Starbase, where it was caught by the 'chopstick' arms on its launch tower). —Brett Tingley, Space.com, 27 June 2025

The company plans to reuse the booster on a future mission. —Matthew Glasser, ABC News, 25 June 2025

The first-stage booster flew for the 25th time, landing on the droneship A Shortfall of Gravitas. —Richard Tribou, The Orlando Sentinel, 23 June 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