1an ornamental tablet, typically of metal, porcelain, or wood, that is fixed to a wall or other surface in commemoration of a person or event.
2 [mass noun] a sticky deposit on teeth in which bacteria proliferate:plaque around gum margins can lead to gingivitis
3 Medicine a small, distinct, typically raised patch or region on or within the body resulting from local damage or deposition of material, such as a fatty deposit on an artery wall in atherosclerosis or a site of localized damage of brain tissue in Alzheimer’s disease.
Microbiology a clear area in a cell culture caused by the inhibition of growth or destruction of cells by an agent such as a virus.
