(uncountable) The part of anything that hangs loose, having no strain upon it.

(countable) A tidal marsh or shallow that periodically fills and drains.

(uncountable, psychotherapy) Unconditional listening attention given by client to patient.

Attributive form of slacks (“semi-formal trousers”).

(rail transport) A temporary speed restriction where track maintenance or engineering work is being carried out at a particular place.

(countable) A valley, or small, shallow dell.

(mining) Small coal; coal dust.

(transitive, intransitive) To slacken.

To lose cohesion or solidity by a chemical combination with water; to slake.

(normally said of a rope) Lax; not tense; not firmly extended.

Weak; not holding fast.

Moderate in temperature and speed.

Lacking diligence or care; not earnest or eager.

Not active or busy, successful, or violent.

Excess; surplus to requirements.

(slang, Caribbean, Jamaica) Vulgar; sexually explicit, especially in dancehall music.

(linguistics) Lax.

Slackly.