The Collaborative International Dictionary of English v.0.48:

Imide \Im"ide\, n. (Chem.)
   A compound with, or derivative of, the imido group; specif.,
   a compound of one or more acid radicals with the imido group,
   or with a monamine; hence, also, a derivative of ammonia, in
   which two atoms of hydrogen have been replaced by divalent
   basic or acid radicals; -- frequently used as a combining
   form; as, succinimide.
   [1913 Webster]

WordNet (r) 3.0 (2006):

imide
    n 1: any of a class of organic compounds that contain the
         divalent radical -CONHCO-