Source : Webster's Revised Unabridged Dictionary (1913)

Parsnip \Pars"nip\, n. [OE. parsnepe, from a French form, fr. L.
   pastinaca; cf. pastinare to dig up, pastinum a kind of
   dibble; cf. OF. pastenade, pastenaque.] (Bot.)
   The aromatic and edible spindle-shaped root of the cultivated
   form of the Pastinaca sativa, a biennial umbelliferous plant
   which is very poisonous in its wild state; also, the plant
   itself.

   {Cow parsnip}. See {Cow parsnip}.

   {Meadow parsnip}, the European cow parsnip.

   {Poison parsnip}, the wild stock of the parsnip.

   {Water parsnip}, any plant of the umbelliferous genus {Sium},
      the species of which are poisonous.

Cow parsnip \Cow" pars`nip\ (-n?p). (Bot.)
   A coarse umbelliferous weed of the genus {Heracleum} ({H.
   sphondylium} in England, and {H. lanatum} in America).

Source : WordNet®

cow parsnip
     n : tall coarse plant having thick stems and cluster of white to
         purple flowers [syn: {hogweed}, {Heracleum sphondylium}]