1 : flowing with little speed as e.g. at the turning of the tide; "slack water"
2 : not tense or taut; "the old man's skin hung loose and grey"; "slack and wrinkled skin"; "slack sails"; "a slack rope"; "a slack grip"
3 : lacking in rigor or strictness; "such lax and slipshod ways are no longer acceptable"; "lax in attending classes"; "slack in maintaining discipline"
nom
1 : a cord or rope or cable that is hanging loosely; "he took up the slack"
2 : a stretch of water without current or movement
3 : a soft wet area of low-lying land that sinks underfoot