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]

WordNet (r) 3.0 (2006):

Asteridae
    n 1: a group of mostly sympetalous herbs and some trees and
         shrubs mostly with 2 fused carpels; contains 43 families
         including Campanulales; Solanaceae; Scrophulariaceae;
         Labiatae; Verbenaceae; Rubiaceae; Compositae; sometimes
         classified as a superorder [syn: Asteridae, subclass
         Asteridae]