'Slackness' definitions:

Definition of 'slackness'

From: WordNet
noun
Weakness characterized by a lack of vitality or energy [syn: inanition, lassitude, lethargy, slackness]
noun
The quality of being loose (not taut); "he hadn't counted on the slackness of the rope" [syn: slack, slackness]
noun
The quality of being lax and neglectful [syn: laxness, laxity, remissness, slackness]

Definition of 'Slackness'

From: GCIDE
  • Slackness \Slack"ness\, n. The quality or state of being slack. [1913 Webster]