: 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 group’s work was used to guide the expansion of the primary COVID-19 vaccine schedule to school-age children in 2021, and booster recommendations in fall 2022.
—
Deidre McPhillips, CNN Money, 18 Sep. 2025
Eggo waffles now come with more protein, Shark's launched a new cordless cleaner and Gain's got new scent boosters to keep your laundry smelling fresh.
—Adam Mills, MSNBC Newsweek, 17 Sep. 2025
The same prep work will also be done with Super Heavy, the huge booster that makes up the bottom half of the fully reusable, stainless-steel Starship.
—Mike Wall, Space.com, 17 Sep. 2025
Last month, the American College of Obstetricians and Gynecologists (ACOG) reaffirmed its stance that women should get a COVID vaccine or booster while pregnant, trying to get pregnant, postpartum, or lactating.
—Yasmin Tayag, The Atlantic, 16 Sep. 2025
See All Example Sentences for booster
Examples are automatically compiled from online sources to
show current usage.
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Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
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Deidre McPhillips, CNN Money, 18 Sep. 2025
Eggo waffles now come with more protein, Shark's launched a new cordless cleaner and Gain's got new scent boosters to keep your laundry smelling fresh.
—Adam Mills, MSNBC Newsweek, 17 Sep. 2025
The same prep work will also be done with Super Heavy, the huge booster that makes up the bottom half of the fully reusable, stainless-steel Starship.
—Mike Wall, Space.com, 17 Sep. 2025
Last month, the American College of Obstetricians and Gynecologists (ACOG) reaffirmed its stance that women should get a COVID vaccine or booster while pregnant, trying to get pregnant, postpartum, or lactating.
—Yasmin Tayag, The Atlantic, 16 Sep. 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 Sep. 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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