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

• advocate
• advocator
• apostle
• backer
• champion
• espouser
• exponent
• expounder
• friend
• gospeler
• gospeller
• herald
• hierophant
• high priest
• paladin
• promoter
• proponent
• protagonist
• supporter
• true believer
• tub-thumper
• white knight

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 vehicle consists of two elements, both of which are designed to be fully and rapidly reusable — a first-stage booster called Super Heavy and a 171-foot-tall (52 meters) upper-stage spacecraft known as Starship, or simply Ship. —Mike Wall, Space.com, 19 June 2025

Known as Ship 36, SpaceX was planning to launch the Starship around the end of this month on a huge Super Heavy booster, in what would have been the rocket's 10th test fight. —June 19, CBS News, 19 June 2025

The first-stage booster made its ninth flight landing on the droneship A Shortfall of Gravitas, marking its 100th booster catch. —Richard Tribou, The Orlando Sentinel, 18 June 2025

At its highest point, the vehicle extended aerodynamic fins akin to those used on SpaceX's reusable Falcon 9 and Super Heavy boosters. —ArsTechnica, 18 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