noun (n)

• the spatial property of being crowded together(noun.attribute)

  Synonym:
  concentration, denseness, density, tightness
  Antonym:
  dispersion, distribution
  

  source: wordnet30
• the consistency of a compact solid(noun.attribute)

  source: wordnet30
• The state or quality of being compact; close union of parts; density.(noun)

  source: webster1913