Akademik

slackness
noun
1. weakness characterized by a lack of vitality or energy
Syn: ↑inanition, ↑lassitude, ↑lethargy
Hypernyms: ↑weakness
2. the quality of being lax and neglectful
Syn: ↑laxness, ↑laxity, ↑remissness
Derivationally related forms: ↑slack, ↑remiss (for: ↑remissness), ↑lax (for: ↑laxity), ↑lax (for: ↑laxness)
Hypernyms: ↑negligence, ↑neglect, ↑neglectfulness
3. the quality of being loose (not taut)
-

he hadn't counted on the slackness of the rope

Syn: ↑slack
Derivationally related forms: ↑slack, ↑slack (for: ↑slack)
Hypernyms: ↑looseness, ↑play

Useful english dictionary. 2012.