# slack

/ˈsɫæk/ (US) · /slˈæk/ (UK)

Source: https://englishreference.com/word/slack
Updated: 2026-08-15

## Senses

### 1. loose or not tight

adjective · CEFR B2

not pulled tight; hanging loose.

For teachers: lacking tension; not firmly extended or taut.

- The rope went slack when the boat reached the dock.
- The climber felt the safety line go slack for a terrifying second before his partner regained control of the belay device.

### 2. not busy

adjective · CEFR B2

not active or having little work to do.

For teachers: characterized by a lack of activity, business, or productivity.

- Business is usually slack during the cold winter months.
- During the slack season, the factory operates on a four-day week to avoid laying off permanent staff members.

### 3. lazy or careless

adjective · CEFR C1 · Informal

not showing enough care or effort.

For teachers: lacking in diligence, precision, or earnestness.

- He has been getting a bit slack with his homework recently.
- The supervisor warned that slack standards in safety protocols would lead to immediate disciplinary action for the entire shift.

### 4. to work slowly or lazily

verb · CEFR B2 · Informal

to work slowly or avoid doing your work.

For teachers: to avoid work or effort; to shirk one's duties.

- If you slack off now, you will never finish the project on time.
- Management noticed that several employees began to slack off once the quarterly targets had been met.

Usage: Often used as the phrasal verb 'slack off'.

### 5. loose part or extra space

noun · CEFR B2

the part of a rope or wire that is not tight; also, extra time or money you can use.

For teachers: the loose part of a rope or cable; figuratively, surplus resources or capacity within a system.

- When the manager left, the rest of the team had to pick up the slack.
- The project manager built some slack into the schedule to account for potential delays in the supply chain.

Usage: Commonly used in the idiom 'to pick up the slack'.

### 6. coal dust

noun · CEFR C2 · Technical

very small pieces of coal or coal dust.

For teachers: coal screenings or dust, often considered of lower quality than lump coal.

- The miners cleared the slack from the bottom of the cart.
- The industrial furnace was specifically designed to burn coal slack, which was significantly cheaper than high-grade anthracite.

### 7. software platform

noun · CEFR B1

a popular computer program used by teams to talk and work together.

For teachers: a proprietary business communication platform offering IRC-style features, including persistent chat rooms organized by topic.

- I will send you the files over Slack later this afternoon.
- The company migrated all internal communications to Slack to reduce the volume of unnecessary emails between departments.

## Examples

- Pull the rope to take up the slack.
- The manager hired temporary staff to pick up the slack during the busy holiday season.
- In project management, identifying the slack in a schedule allows for more flexible resource allocation without risking the final deadline.

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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.