# booster

/ˈbustɝ/ (US) · /bˈuːstɐ/ (UK)

Source: https://englishreference.com/word/booster
Updated: 2026-06-20

## Senses

### 1. medical dose

noun · CEFR B2

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

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

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

### 2. rocket engine

noun · CEFR B2

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

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

- The rocket's boosters fell away into the ocean once the craft reached the upper atmosphere.
- Engineers monitored the solid rocket boosters closely during the first two minutes of flight to ensure the trajectory remained within safety parameters.

### 3. a supporter

noun · CEFR C1 · American English

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

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

- The local business boosters raised money to renovate the high school football field.
- As a lifelong booster of the university's arts programme, she donated a significant portion of her estate to the new gallery.

Teaching tip: In the US, this often refers specifically to members of a 'booster club' who raise money for school sports.

### 4. child's seat

noun · CEFR B2

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

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

- The restaurant provided a booster so the toddler could reach the table.
- Safety regulations require children of a certain height to remain in a booster until the vehicle's shoulder belt fits them correctly.

### 5. linguistic intensifier

noun · CEFR C2 · Academic · Technical

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

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

- In the sentence 'I am so happy', the word 'so' acts as a booster.
- The researcher analysed the frequency of boosters in persuasive writing to determine how they influenced the reader's perception of authority.

### 6. a thief

noun · CEFR C2 · Slang · American English

a person who steals items from a shop.

For teachers: a person who engages in shoplifting or professional theft.

- The security guard caught the booster trying to leave with three expensive jackets.
- The police identified a ring of professional boosters who had been targeting high-end boutiques across the metropolitan area.

### 7. to give a shot

verb · CEFR C1 · Informal

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

For teachers: to administer a booster dose of a vaccine to an individual.

- The clinic is planning to booster all the residents at the nursing home next week.
- The health department aimed to booster the entire vulnerable population before the winter flu season peaked.

## Examples

- She got a booster shot last week.
- The doctor recommended a booster to keep the vaccine protection strong.
- The political campaign relied on a final media booster to sway undecided voters before the election.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.