The Collaborative International Dictionary of English v.0.48:

Scammony \Scam"mo*ny\ (sk[a^]m"m[-o]*n[y^]), n. [F.
   scammon['e]e, L. scammonia, scammonea, Gr. skammwni`a.]
   1. (Bot.) A species of bindweed or Convolvulus
      (Convolvulus Scammonia).
      [1913 Webster]

   2. An inspissated sap obtained from the root of the
      Convolvulus Scammonia, of a blackish gray color, a
      nauseous smell like that of old cheese, and a somewhat
      acrid taste. It is used in medicine as a cathartic.
      [1913 Webster]

WordNet (r) 3.0 (2006):

scammony
    n 1: tropical American morning glory [syn: scammony, Ipomoea
         orizabensis]
    2: resin from the root of Convolvulus scammonia
    3: twining plant of Asia Minor having cream-colored to purple
       flowers and long thick roots yielding a cathartic resin [syn:
       scammony, Convolvulus scammonia]