The Collaborative International Dictionary of English v.0.48:

Perspicacious \Per`spi*ca"cious\ (p[~e]r`sp[i^]*k[=a]"sh[u^]s),
   a. [L. perspicax, -acis, fr. perspicere to look through: cf.
   F. perspicace. See Perspective.]
   1. Having the power of seeing clearly; quick-sighted; sharp
      of sight.
      [1913 Webster]

   2. Fig.: Of acute discernment; keen.
      [1913 Webster] -- Per`spi*ca"cious*ly, adv. --
      Per`spi*ca"cious*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

perspicaciousness
    n 1: intelligence manifested by being astute (as in business
         dealings) [syn: shrewdness, astuteness, perspicacity,
         perspicaciousness]