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

Before another launch is attempted, Musk added in a follow-up post that two of the booster's 33 Raptor-class engines will be removed and replaced. — Eric Lagatta, USA Today, 17 July 2026

Blue Origin, although its New Glenn booster is temporarily grounded, has also demonstrated the ability to both land and re-launch a large orbital booster. — Eric Berger, ArsTechnica, 17 July 2026

For Flight 13, after separating from Starship high above the Earth, the Super Heavy V3 would fly back to perform a pinpoint splashdown in the Gulf of Mexico—a landing that the booster failed to stick during Flight 12. — Lee Billings & Claire Cameron, Scientific American, 16 July 2026

And while reusing first-stage rocket boosters (like the Super Heavy) is firmly within SpaceX’s wheelshouse, the company has never reused the upper stage of a rocket. — Jackie Wattles, CNN Money, 16 July 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