The Collaborative International Dictionary of English v.0.48:

Entablature \En*tab"la*ture\ (?; 135), n. [OF. entablature: cf.
   It intavolatura, fr. LL. intabulare to construct a basis; L.
   in + tabulatum board work, flooring, fr. tabula. See
   Table.] (Arch.)
   The superstructure which lies horizontally upon the columns.
   See Illust. of Column, Cornice.
   [1913 Webster]

   Note: It is commonly divided into architrave, the part
         immediately above the column; frieze, the central
         space; and cornice, the upper projecting moldings.
         --Parker.
         [1913 Webster]

WordNet (r) 3.0 (2006):

entablature
    n 1: (architecture) the structure consisting of the part of a
         classical temple above the columns between a capital and
         the roof