# smack

/ˈsmæk/ (US) · /smˈæk/ (UK)

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

## Senses

### 1. to hit

verb · CEFR B2

to hit someone or something with the flat part of your hand.

For teachers: to strike someone or something with a sharp blow, typically using the palm of the hand.

- He accidentally smacked his head against the low shelf while standing up.
- The waves smacked against the side of the wooden pier with surprising force as the storm rolled in from the coast.

### 3. a sharp blow

noun · CEFR B2

the act or sound of hitting something with your hand.

For teachers: a sharp, resounding blow or the specific sound produced by such an impact.

- We heard the loud smack of the ball hitting the wall.
- The book fell onto the hardwood floor with a loud smack, startling everyone in the quiet library.

### 4. heroin

noun · CEFR C2 · Slang

a slang name for the illegal drug heroin.

For teachers: a slang term for heroin. Uncountable in this sense.

- The documentary explored the lives of people addicted to smack in the 1970s.
- Undercover officers were focused on disrupting the local distribution of smack and other Class A substances.

### 5. a loud kiss

noun · CEFR C1 · Informal

a loud kiss made by pressing the lips together and then opening them quickly.

For teachers: a loud, audible kiss, or the sound produced by such a kiss.

- She gave her grandson a big smack on the cheek.
- The aunt greeted each of her nephews with a noisy smack on the forehead before ushering them into the house.

### 6. exactly or directly

adverb · CEFR B2 · Informal

exactly in a certain place or directly against something.

For teachers: directly, squarely, or precisely; often used to describe a physical collision or a specific location.

- The ball landed smack in the middle of the flower bed.
- The cyclist rode smack into the back of a parked van because he was looking at his phone.

### 7. computing stack

noun · CEFR C2 · Technical

a set of software tools used to handle large amounts of data.

For teachers: An acronym for a data processing stack consisting of Spark, Mesos, Akka, Cassandra, and Kafka.

- The engineering team decided to use the SMACK stack for their new real-time analytics project.
- Implementing the SMACK stack allowed the company to process millions of events per second with high availability and fault tolerance.

Usage: Usually written in all caps as SMACK.

## Examples

- He smacked the table with his hand to get everyone's attention.
- The child got into trouble for trying to smack his younger brother during the argument.
- The waves continued to smack against the hull of the small boat, threatening to overturn it as the storm intensified throughout the night.

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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.