plaque

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A flat plate, slab, or disk that is ornamented or engraved for mounting, as on a wall for decoration or on a monument for information.
2. n. A small pin or brooch worn as an ornament or a badge of membership.
3. n. Pathology A small disk-shaped formation or growth; a patch.
4. n. A deposit of fatty material on the inner lining of an arterial wall, characteristic of atherosclerosis.
5. n. A scaly patch formed on the skin by psoriasis.
6. n. A film of mucus and bacteria on a tooth surface.
7. n. A clear, often round patch of lysed cells in an otherwise opaque layer of a bacteria or cell culture.

Century Dictionary and Cyclopedia

1. n. An ornamental plate; a brooch; the plate of a clasp.
2. n. A square, oblong, or circular tablet of bronze or silver, the largest dimension of which extends to three or four inches, ornamented in relief with some religious, mythological, allegorical, or decorative subject. The Pax, from which the plaque originated, is set in an ornamental framework; the Renaissance plaque was intended to be hung up or inserted in a box or a piece of furniture, or, if circular, to be worn as a hat-medallion. Also called plaquette.
3. n. Any tablet or distinctly flat plate of metal or porcelain, whether plain or ornamented; partieularly. an ornamental circular plate intended for a wall-decoration. See cut in next column.
4. n. The especial decoration of a high rank in many honorary orders. See star, insignia, order, 6 .
5. n. In anatomy and zoology, a small flat object of round figure, as a blood-disk; a little plate. Also plaquette
6. n. A patch.
7. n. A billon or silver coin current in the fourteenth and fifteenth centuries in Brabant, Liège, Lorraine, and France.

Wiktionary

1. n. 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.
2. n. uncountable An accumulation of biofilm, or bacteria on teeth.
3. n. uncountable, medicine Atheroma, an accumulation in artery walls made up of macrophage cells and debris containing lipids, (cholesterol and fatty acids), calcium, and connective tissue.
4. n. biology A clearing in a bacterial lawn caused by a virus.

GNU Webster's 1913

1. n. 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.

WordNet 3.0

1. n. (pathology) a small abnormal patch on or inside the body
2. n. a memorial made of brass