Dictionary Definition:

“An organic compound containing the group —C(O)NH2, derived from ammonia by replacement of a hydrogen atom by an acyl group.”

Selected from OxfordDictionaries.com

Functional Definition:

Amides like amines originate from the ammonia NH3 compound but unlike the amine with three R functional groups one of the R groups is an acyl or -CO. group. Bellow are two amide molecules with their IUPAC names. When differentiating amines and amides it is helpful to remember that an amide is an amine with an acyl group.

Figure courtesy of Fvasconelloas of Wikipedia Commons