The Collaborative International Dictionary of English v.0.48:

Capacious \Ca*pa"cious\ (k[.a]*p[=a]"sh[u^]s), a. [L. capax,
   -acis, fr. capere to take. See Heave.]
   1. Having capacity; able to contain much; large; roomy;
      spacious; extended; broad; as, a capacious vessel, room,
      bay, or harbor.
      [1913 Webster]

            In the capacious recesses of his mind. --Bancroft.
      [1913 Webster]

   2. Able or qualified to make large views of things, as in
      obtaining knowledge or forming designs; comprehensive;
      liberal. "A capacious mind." --Watts.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "capacious":
   abundant, ample, amplitudinous, broad, commodious, comprehensive,
   copious, deep, expandable, expansive, extended, extending,
   extensile, extensive, far-reaching, generous, infinite, plentiful,
   roomy, spacious, spreading, vast, voluminous, wide, widespread