The Collaborative International Dictionary of English v.0.48:

Coriander \Co`ri*an"der\ (k?`r?-?n"d?r), n. [L. coriandrum, fr.
   Gr. ????, ????, perh. fr. ??? bug, on account of the buglike
   or fetid smell of its leaves: cf. F. coriandre.] (Bot.)
   An umbelliferous plant, the Coriandrum sativum, the fruit
   or seeds of which have a strong smell and a spicy taste, and
   in medicine are considered as stomachic and carminative.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

cilantro \cilantro\ n.
   1. an Old World herb (Coriandrum sativum) with aromatic
      parsleylike leaves and seed.

   Syn: coriander, coriander plant, Chinese parsley, Coriandrum
        sativum.
        [WordNet 1.5]

   2. a parsleylike herb used as seasoning or garnish.

   Syn: coriander, Chinese parsley.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Coriandrum sativum
    n 1: Old World herb with aromatic leaves and seed resembling
         parsley [syn: coriander, coriander plant, Chinese
         parsley, cilantro, Coriandrum sativum]