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English definition of “booster”

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booster

noun [C] uk   /ˈbuː.stər/ us    /-stɚ/

booster noun [C] (IMPROVEMENT)

something that improves or increases something: a confidence/morale booster

booster noun [C] (ENGINE)

an engine on a spacecraft that gives extra power for the first part of a flight: a rocket booster

booster noun [C] (DRUG)

a small amount of a substance that is given to increase the effect of the same substance given some time before, to continue to protect a person from illness: a polio booster
(Definition of booster from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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