plaque 
/ˈplæk/ noun
plural plaques /ˈplæk/ noun 1 [count] : a flat, thin piece of metal or wood with writing on it that is used especially as a reminder of something (such as a historic event or an achievement)
▪ A bronze plaque marked the city's oldest building. ▪ They gave him a plaque in honor of his 30 years of service. 2 a [noncount] : a thin coating that forms on teeth and contains bacteria
▪ Brushing your teeth prevents the buildup of plaque.
b [count] medical : a change in brain tissue that occurs in Alzheimer's disease
▪ The scientists are studying the way the plaques form.
c [noncount] medical : a harmful material that can form in arteries and be a cause of heart disease
▪ A bronze plaque marked the city's oldest building. ▪ They gave him a plaque in honor of his 30 years of service.
▪ Brushing your teeth prevents the buildup of plaque.
b [count] medical : a change in brain tissue that occurs in Alzheimer's disease
▪ The scientists are studying the way the plaques form.
c [noncount] medical : a harmful material that can form in arteries and be a cause of heart disease
