plural plaques
1
: 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
: a thin coating that forms on teeth and contains bacteria
Brushing your teeth prevents the buildup of plaque.
b
medical
: a change in brain tissue that occurs in Alzheimer's disease
The scientists are studying the way the plaques form.
c
medical
: a harmful material that can form in arteries and be a cause of heart disease
Cite this Entry
“Plaque.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/plaque. Accessed 20 Jun. 2026.
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