Source : Webster's Revised Unabridged Dictionary (1913)

Ingrate \In"grate`\ (?; 277), a. [L. ingratus. See
   {Ingrateful}.]
   Ingrateful. [Obs. or Poetic] --Bacon.

Ingrate \In"grate`\, n.
   An ungrateful person. --Milton.

Source : WordNet®

ingrate
     n : a person who shows no gratitude [syn: {thankless wretch}, {ungrateful
         person}]