firmness vs slack

firmness

noun
  • security; steadfastness; good grip 

  • strictness; mental strength 

  • physical durability; rigidness (of material) 

slack

noun
  • Unconditional listening attention given by client to patient. 

  • A temporary speed restriction where track maintenance or engineering work is being carried out at a particular place. 

  • A tidal marsh or shallow that periodically fills and drains. 

  • The part of anything that hangs loose, having no strain upon it. 

  • Small coal; coal dust. 

  • A valley, or small, shallow dell. 

adj
  • Moderately warm. 

  • Vulgar; sexually explicit, especially in dancehall music. 

  • Not active or busy, successful, or violent. 

  • Excess; surplus to requirements. 

  • Lax; not tense; not firmly extended. 

  • Lacking diligence or care; not earnest or eager. 

  • Lax. 

  • Moderate in speed. 

  • Weak; not holding fast. 

verb
  • To slacken. 

  • To lose cohesion or solidity by a chemical combination with water; to slake. 

adv
  • Slackly. 

How often have the words firmness and slack occurred in a corpus of books? (source: Google Ngram Viewer )