The Collaborative International Dictionary of English v.0.48:
Substantialness \Sub*stan"tial*ness\, n. The quality or state of being substantial; as, the substantialness of a wall or column. [1913 Webster]WordNet (r) 3.0 (2006):
substantialness n 1: the quality of being substantial or having substance [syn: substantiality, substantialness, solidness] [ant: insubstantiality]