slack (Noun) — Dust consisting of a mixture of small coal fragments and coal dust and dirt that sifts out when coal is passed over a sieve.
slack (Noun) — A noticeable deterioration in performance or quality. ex. "a gradual slack in output"
slack (Noun) — A stretch of water without current or movement. ex. "suddenly they were in a slack and the water was motionless"
slack (Noun) — A soft wet area of low-lying land that sinks underfoot.
slack (Noun) — The quality of being loose (not taut). ex. "he hadn't counted on the slack of the rope"
slack (Noun) — A cord, rope or cable that is hanging loosely. ex. "he took up the slack"
slack (Verb) — Avoid responsibilities and work, be idle.
slack (Verb) — Be inattentive to, or neglect. ex. "He slacks his attention"
slack (Verb) — Release tension on. ex. "slack the rope"
slack (Verb) — Make less active or fast. ex. "He slacked his pace as he got tired"
slack (Verb) — Become slow or slower.
slack (Verb) — Make less active or intense.
slack (Verb) — Become less in amount or intensity. ex. "The storm slacked off"
slack (Verb) — Cause to heat and crumble by treatment with water. ex. "slack lime"
slack (Adjective) — Not tense or taut. ex. "slack and wrinkled skin" ex. "slack sails" ex. "a slack rope"
slack (Adjective) — Flowing with little speed as e.g. at the turning of the tide. ex. "slack water"
slack (Adjective) — Lacking in rigour or strictness. ex. "slack in maintaining discipline"