Definition of booster in English:


Syllabification: boost·er
Pronunciation: /ˈbo͞ostər


1A person or thing that helps increase or promote something, in particular.
More example sentences
  • Volunteer work, in particular, can be an immense confidence booster.
  • Products containing ephedra are often promoted as energy boosters or aids to controlling weight.
  • It is also high in vitamins, minerals, protein, phytochemicals and chlorophyll, and it may work as a cancer preventative and brain booster.
1.1North American A keen promoter of a person, organization, or cause: [as modifier]: athletic booster clubs
More example sentences
  • In a country where it is illegal to organize many types of public meetings, fans formed booster clubs and canvassed malls to court prospective voters.
  • In fact, if it weren't for parental involvement as sponsors, coaches, booster club participants, etc. most programs would not even survive.
  • In the early twentieth century, booster organizations that favored particular water projects proliferated.
1.2 [in combination] A source of help or encouragement: job fairs are a great morale booster
1.3 Medicine A dose of an immunizing agent increasing or renewing the effect of an earlier one.
More example sentences
  • Dr. Robbins said that efforts to increase the efficacy of the vaccines will include studies on the effectiveness of a booster dose of the vaccine given one year later.
  • Young children who have not received all five doses of the vaccine may require a booster dose if exposed to an infected family member.
  • I had a booster vaccination last year, needed every ten years.
1.4The first stage of a rocket or spacecraft, used to give initial acceleration.
More example sentences
  • The camera will be turned on fifteen minutes prior to launch and will show the orbiter and solid rocket boosters on the launch pad.
  • The ground crews will also be monitoring the performance of the orbiter, solid rocket boosters and ground system while the tank is filled with the ultra-cold liquids.
  • In the first scenario, personal spaceflight will use lower-cost versions of classic boosters and spacecraft.
1.5A device for increasing electrical voltage or signal strength.
More example sentences
  • Antenna boosters help to strengthen the signal between a cell tower and your phone.
  • A booster circuit uses a source voltage to generate a boosted voltage that is higher than the source voltage.
  • Antenna booster for areas with weak signals are another good choice.
2North American informal A shoplifter.

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Word of the day retroflex
Pronunciation: ˈrɛtrə(ʊ)flɛks
turned backwards