Source : Webster's Revised Unabridged Dictionary (1913)

Plaque \Plaque\, n. [F. Cf. {Plack}, and see {Placard}.]
   Any flat, thin piece of metal, clay, ivory, or the like, used
   for ornament, or for painting pictures upon, as a slab,
   plate, dish, or the like, hung upon a wall; also, a smaller
   decoration worn on the person, as a brooch.

Source : WordNet®

plaque
     n 1: (pathology) a small abnormal patch on or inside the body
     2: a memorial made of brass [syn: {brass}, {memorial tablet}]