The Collaborative International Dictionary of English v.0.48:

Dicotyledonae \Dicotyledonae\ n. (Bot.)
   a class of plants comprising those seed plants that produce
   an embryo with two cotyledons and net-veined leaves; divided
   into six (not always well distinguished) subclasses (or
   superorders): Magnoliidae and Hamamelidae (considered
   primitive); Caryophyllidae (an early and distinctive
   offshoot); and three more or less advanced groups:
   Dilleniidae; Rosidae; Asteridae.

   Syn: Dicotyledones, class Dicotyledones, class Dicotyledonae,
        Magnoliopsida, class Magnoliopsida.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Dilleniidae \Dilleniidae\ n.
   a group of families of more or less advanced trees and shrubs
   and herbs having either polypetalous or gamopetalous corollas
   and often with ovules attached to the walls of the ovary; it
   contains 69 families including Ericaceae and Cruciferae
   and Malvaceae; it is sometimes classified as a superorder.

   Syn: subclass Dilleniidae.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Dilleniidae
    n 1: a group of families of more or less advanced trees and
         shrubs and herbs having either polypetalous or gamopetalous
         corollas and often with ovules attached to the walls of the
         ovary; contains 69 families including Ericaceae and
         Cruciferae and Malvaceae; sometimes classified as a
         superorder [syn: Dilleniidae, subclass Dilleniidae]