ENGLISH
REFERENCE

booster

n. · v.
US //ˈbustɝ// UK //bˈuːstɐ// boost·er
  1. 1 medical dose (n.)
    B2 Upper Intermediate Medicine

    an extra dose of a vaccine given to keep the protection working.

    an additional dose of a vaccine or immunising agent administered to maintain or increase the level of immunity.

    Example

    The doctor recommended a booster before I travelled to a country with high infection rates.

    Example

    Public health officials debated the optimal timing for the booster to ensure maximum antibody response across the elderly population.

    Usage

    Often used as a compound noun: 'booster shot'.
    • booster shot
    • re vaccination
  2. 2 rocket engine (n.)
    B2 Upper Intermediate Science

    the first part of a rocket that provides the power to lift off.

    the initial stage of a multistage rocket or an auxiliary engine providing supplemental thrust during liftoff.

    Example

    The rocket's boosters fell away into the ocean once the craft reached the upper atmosphere.

    Example

    Engineers monitored the solid rocket boosters closely during the first two minutes of flight to ensure the trajectory remained within safety parameters.
    • thruster
    • rocket motor
Show 5 more sensesShow fewer
  1. 3 a supporter (n.)
    C1 Advanced American English

    someone who actively supports or promotes a team, school, or person.

    an enthusiastic supporter or promoter of a specific cause, institution, or individual.

    Example

    The local business boosters raised money to renovate the high school football field.

    Example

    As a lifelong booster of the university's arts programme, she donated a significant portion of her estate to the new gallery.

    Teacher's tip

    In the US, this often refers specifically to members of a 'booster club' who raise money for school sports.
  2. 4 child's seat (n.)
    B2 Upper Intermediate

    a small seat placed on a chair or car seat to help a child sit higher.

    a removable seat used to raise a child to a height where they can sit at a table or safely use a car seatbelt.

    Example

    The restaurant provided a booster so the toddler could reach the table.

    Example

    Safety regulations require children of a certain height to remain in a booster until the vehicle's shoulder belt fits them correctly.
    • booster seat
  3. 5 linguistic intensifier (n.)
    C2 Proficiency Academic Technical Linguistics

    a word like 'very' or 'extremely' that makes another word stronger.

    a lexical item used to amplify or strengthen the force of an utterance.

    Example

    In the sentence 'I am so happy', the word 'so' acts as a booster.

    Example

    The researcher analysed the frequency of boosters in persuasive writing to determine how they influenced the reader's perception of authority.
  4. 6 a thief (n.)
    C2 Proficiency Slang American English

    a person who steals items from a shop.

    a person who engages in shoplifting or professional theft.

    Example

    The security guard caught the booster trying to leave with three expensive jackets.

    Example

    The police identified a ring of professional boosters who had been targeting high-end boutiques across the metropolitan area.
  5. 7 to give a shot (v.)
    C1 Advanced Informal Medicine

    to give someone an extra medical dose to keep them protected.

    to administer a booster dose of a vaccine to an individual.

    Example

    The clinic is planning to booster all the residents at the nursing home next week.

    Example

    The health department aimed to booster the entire vulnerable population before the winter flu season peaked.
    • re vaccinate

© 2026 English Reference