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

That was followed by another mishap in September, when the booster originally intended for Alpha's seventh flight exploded during prelaunch testing. —Josh Dinner, Space.com, 20 Feb. 2026

Crewed mission The wet dress rehearsal concluded late Thursday following two terminal counts, despite a brief pause during the final run caused by a booster avionics voltage issue. —Mrigakshi Dixit, Interesting Engineering, 20 Feb. 2026

Using the high-res ADR and production sound mixer Greg Chapman’s recordings of Elordi’s performance, Robitaille gave Cooke and re-recording mixer Brad Zoern two different subsonic booster tracks to utilize. —Jim Hemphill, IndieWire, 20 Feb. 2026

This marked the 21st flight for the first-stage booster, the most in the booster fleet, having previously flown on human spaceflight missions Inspiration4 and Axiom Space’s Ax-1 among others. —Richard Tribou, The Orlando Sentinel, 20 Feb. 2026

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