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

According to the store, Target will accept and recycle all types of seats from infant car seats, convertible car seats, car seat bases, harness or booster car seats. —Fernando Cervantes Jr, USA Today, 11 Sep. 2025

Yohimbine, derived from plant roots or tree bark, is sometimes marketed as an energy- or libido-booster. —Sam Manzella, Flow Space, 10 Sep. 2025

Mane Attractions Frizz fighters, volume boosters, curl definers—these haircare heroes do it all and leave your strands looking salon-level lush. —Jackie Fields, People.com, 9 Sep. 2025

Programs should be put in place to enhance boosters and reduce drainers with leaders, workplace managers and human resources specialists working together to create the knowledge, environments, habits and rituals to enable peak performance and wellbeing. —Andrew Mawson, Forbes.com, 8 Sep. 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