'Compactness' definitions:

Definition of 'compactness'

From: WordNet
noun
The spatial property of being crowded together [syn: concentration, density, denseness, tightness, compactness] [ant: dispersion, distribution]
noun
The consistency of a compact solid

Definition of 'Compactness'

From: GCIDE
  • Compactness \Com*pact"ness\, n. The state or quality of being compact; close union of parts; density. [1913 Webster]