Plaque
mid 19th century: from French, from Dutch plak ‘tablet’, from plakken ‘to stick’.
wiktionary
Borrowed from French plaque(“plate, sheet (of metal); slab (of marble); bacteria on teeth”), from French plaquer, Middle French plaquer(“to plate”), [1] 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 *plaggą(“patch”).
The word is cognate with Middle Low German placke, plagge(“small stain, scraps, rags, thin grass”), German Placken(“spot, patch”), Saterland Frisian plak, plakke(“a blow, slap”), Swedish plagg(“clothing, garment”). Compare plack.
etymonline
plaque (n.)
1848, "ornamental plate or tablet," from French plaque "metal plate, coin" (15c.), perhaps through Flemish placke "small coin," from Middle Dutch placke "disk, patch, stain," related to German Placken "spot, patch" (compare placard). Meaning "deposit on walls of arteries" is attested by 1891; that of "bacteria deposits on teeth" is by 1898.
