: 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
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 SpaceX Starship spacecraft is hoisted along the launch tower for stacking atop the Super Heavy booster in preparation for its 11th test flight from the company's complex in Starbase, Texas, on Saturday.
—
Denise Chow, NBC news, 16 Oct. 2025
Both its stages, the Super Heavy booster and the Ship upper stage, successfully returned for pinpoint splashdowns.
—Kaif Shaikh, Interesting Engineering, 15 Oct. 2025
SpaceX teases a return to eye-catching booster landings After using most of its fuel and propelling Starship toward space, the Super Heavy on Monday safely broke away from the upper Starship spacecraft and veered back toward Earth.
—Jackie Wattles, CNN Money, 14 Oct. 2025
During three separate Starship launches since October, SpaceX returned the massive spacecraft's rocket booster at its South Texas launch site to be caught by its giant tower with metal arms.
—Eric Lagatta, USA Today, 14 Oct. 2025
See All Example Sentences for booster
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Denise Chow, NBC news, 16 Oct. 2025
Both its stages, the Super Heavy booster and the Ship upper stage, successfully returned for pinpoint splashdowns.
—Kaif Shaikh, Interesting Engineering, 15 Oct. 2025
SpaceX teases a return to eye-catching booster landings After using most of its fuel and propelling Starship toward space, the Super Heavy on Monday safely broke away from the upper Starship spacecraft and veered back toward Earth.
—Jackie Wattles, CNN Money, 14 Oct. 2025
During three separate Starship launches since October, SpaceX returned the massive spacecraft's rocket booster at its South Texas launch site to be caught by its giant tower with metal arms.
—Eric Lagatta, USA Today, 14 Oct. 2025
See All Example Sentences for booster
Cite this Entry
“Booster.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/booster. Accessed 19 Oct. 2025.
Copy CitationKids Definition
booster
noun
boost·er
ˈbü-stər 
1
: one that boosts
2
: an enthusiastic supporter
3
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)
(2)
b
: synergist sense 1
a chemical acting as a booster to sulfa drugs
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