'Massiveness' definitions:

Definition of 'massiveness'

From: WordNet
noun
An unwieldy largeness [syn: bulkiness, massiveness]
noun
The property of being large in mass [syn: heft, heftiness, massiveness, ponderousness, ponderosity]

Definition of 'Massiveness'

From: GCIDE
  • Massiveness \Mass"ive*ness\, n. The state or quality of being massive; massiness. [1913 Webster]