The Collaborative International Dictionary of English v.0.48:

expansiveness \expansiveness\ n.
   1. a quality characterized by magnificence of scale; as, the
      expansiveness of their extravagant lifestyle was soon
      curtailed.
      [WordNet 1.5]

   2. a friendly open trait of a talkative person.

   Syn: effusiveness.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Expansive \Ex*pan"sive\ ([e^]ks*p[a^]n"s[i^]v), a. [Cf. F.
   expansif.]
   1. Having a capacity or tendency to expand or dilate;
      diffusive; of much expanse; wide-extending; as, the
      expansive force of heat; the expansive quality of air.
      [WordNet sense 1]
      [1913 Webster]

            A more expansive and generous compassion. --Eustace.
      [1913 Webster]

            His forehead was broad and expansive. --Prescott.

   2. causing expansion; as, the expansive force of heat.
      [1913 Webster +PJC]

   3. of much expanse; wide-extending; as, an expansive view of
      the mountains.
      [PJC]

   4. friendly, open, and unrestrained in conversation or
      discourse; -- of people; as, wine made the guest
      expansive. [WordNet sense 4]

   Syn: effusive, talkative.
        [WordNet 1.5]

   5. characterized by exaggerated feelings of euphoria and
      delusions of grandeur. [WordNet sense 3]
      [WordNet 1.5] -- Ex*pan"sive*ly, adv.
      -Ex*pan"sive*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

expansiveness
    n 1: a quality characterized by magnificence of scale or the
         tendency to expand; "the expansiveness of their extravagant
         life style was soon curtailed" [syn: expansiveness,
         expansivity]
    2: a friendly open trait of a talkative person [syn:
       effusiveness, expansiveness, expansivity]