Medical Definition of plaque
1a: a localized abnormal patch on a body part or surface and especially on the skin <psoriatic plaque>b: a sticky usually colorless film on teeth that is formed by and harbors bacteriac: an atherosclerotic lesiond: a histopathologic lesion of brain tissue that is characteristic of Alzheimer's disease and consists of a dense proteinaceous core composed primarily of beta-amyloid that is often surrounded and infiltrated by a cluster of degenerating axons and dendrites—called also senile plaque
2: a visibly distinct and especially a clear or opaque area in a bacterial culture produced by damage to or destruction of cells by a virus
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