The Collaborative International Dictionary of English v.0.48:

Modillion \Mo*dil"lion\, n. [F. modillon, It. modiglione. Cf.
   Module, n.] (Arch.)
   The enriched block or horizontal bracket generally found
   under the cornice of the Corinthian and Composite
   entablature, and sometimes, less ornamented, in the Ionic and
   other orders; -- so called because of its arrangement at
   regulated distances.
   [1913 Webster]

WordNet (r) 3.0 (2006):

modillion
    n 1: (architecture) one of a set of ornamental brackets under a
         cornice