'Steepness' definitions:

Definition of 'steepness'

From: WordNet
noun
The property possessed by a slope that is very steep [syn: abruptness, precipitousness, steepness] [ant: gentleness, gradualness]

Definition of 'Steepness'

From: GCIDE
  • Steepness \Steep"ness\, n.
  • 1. Quality or state of being steep; precipitous declivity; as, the steepnessof a hill or a roof. [1913 Webster]
  • 2. Height; loftiness. [Obs.] --Chapman. [1913 Webster]