What is the meaning of the word "slack"?

Definitions:

a cord or rope or cable that is hanging loosely noun
- They took up the slack.
a stretch of water without current or movement noun
- suddenly they were in a slack and the water was motionless
be inattentive to, or neglect verb
- I slack my attention at times.
cause to heat and crumble by treatment with water verb
- slack lime
flowing with little speed as e.g. at the turning of the tide adjective
- slack water
make less active or fast verb
- I slackened my pace as I became tired.
release tension on verb
- slack the rope
the quality of being loose, not taut noun
- I hadn't counted on the amount of slack in the rope.