The Collaborative International Dictionary of English v.0.48:

Asafetida \As`a*fet"i*da\, Asafoetida \As`a*f[oe]t"i*da\, n.
   [Asa + L. foetidus fetid.]
   The fetid gum resin or inspissated juice of a large
   umbelliferous plant (Ferula asafoetida) of Persia and the
   East Indies. It is used in medicine as an antispasmodic.
   [Written also assafoetida.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

asafoetida
    n 1: the brownish gum resin of various plants; has strong taste
         and odor; formerly used as an antispasmodic [syn:
         asafetida, asafoetida]