: 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 booster flew for the 17th time (3rd booster to do so) and landed on the droneship Just Read the Instructions.
—
Richard Tribou, The Orlando Sentinel, 13 Feb. 2026
Stock up on frozen veggies like broccoli, spinach, and cauliflower: These are nutrient-rich smoothie boosters with a neutral flavor that won’t overpower.
—Lauren O'Connor, Health, 6 Feb. 2026
Agrawal said Roos boosters are already planning to invest more into the program.
—Pj Green, Kansas City Star, 5 Feb. 2026
Most adults who were vaccinated as children don’t need a booster, experts say, but adults who didn’t get the shots as kids can still get vaccinated.
—Mary Ramsey, Charlotte Observer, 5 Feb. 2026
See All Example Sentences for booster
Examples are automatically compiled from online sources to
show current usage.
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Richard Tribou, The Orlando Sentinel, 13 Feb. 2026
Stock up on frozen veggies like broccoli, spinach, and cauliflower: These are nutrient-rich smoothie boosters with a neutral flavor that won’t overpower.
—Lauren O'Connor, Health, 6 Feb. 2026
Agrawal said Roos boosters are already planning to invest more into the program.
—Pj Green, Kansas City Star, 5 Feb. 2026
Most adults who were vaccinated as children don’t need a booster, experts say, but adults who didn’t get the shots as kids can still get vaccinated.
—Mary Ramsey, Charlotte Observer, 5 Feb. 2026
See All Example Sentences for booster
Cite this Entry
“Booster.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/booster. Accessed 15 Feb. 2026.
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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