Princeton's WordNet

1. Dicotyledones, class Dicotyledones, Dicotyledonae, class Dicotyledonae, Magnoliopsida, class Magnoliopsida(noun)

   comprising seed plants that produce an embryo with paired 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