From WordNet (r) 3.0 (2006) [wn]:
plaque
n 1: (pathology) a small abnormal patch on or inside the body
2: a memorial made of brass [syn: brass, memorial tablet,
plaque]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
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.
[1913 Webster]