Sticky white stuff on your teeth with bacteria in it is an example of plaque.
A little brass plate with the name of a donor on it that is attached to a bench the donor paid for is an example of a plaque.
Origin of plaque
- French from Old French metal plate perhaps from Middle Dutch placke disk, patch
From American Heritage Dictionary of the English Language, 5th Edition
- Borrowing from French plaque, derivative of plaquer (“to plate"), from Middle Dutch placken (“to patch, beat metal into a thin plate"), from placke (“disk, patch, stain"), from Old Dutch *plagga (“patch"), from Proto-Germanic *plaggÄ… (“patch"). Cognate with Middle Low German placke, plagge (“small stain, scraps, rags, thin grass"), German Placken (“spot, patch"), Eastern Frisian plak, plakke (“a blow, slap"), Swedish plagg (“clothing, garment"). See plack.