The Collaborative International Dictionary of English v.0.48:

Palladian \Pal*la"di*an\ (p[a^]l*l[=a]"d[i^]*an), prop. a. [From
   Pallas, Athena.]
   1. Of or pertaining to the Greek goddess Athena, also called
      Pallas.
      [PJC]

   2. Pertaining to wisdom or knowledge; -- Athena being the
      goddess of wisdom.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Palladian \Pal*la"di*an\ (p[a^]l*l[=a]"d[i^]*an), prop. n.
   (Arch.)
   A follower of the architectural style of Andrea Palladio.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Palladian \Pal*la"di*an\ (p[a^]l*l[=a]"d[i^]*an), prop. a.
   (Arch.)
   Of, pertaining to, or designating, a variety of the revived
   classic style of architecture, founded on the works of Andrea
   Palladio, an Italian architect of the 16th century; as, a
   Palladian window.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Palladian
    adj 1: referring to or relating to or having the style of
           architecture created by Andrea Palladio; "the much
           imitated arch and column compositions known as the
           Palladian motif"