noun
plaque
PLAK/plæk/
A flat plate displayed as a memorial or decoration.
The bronze plaque bears a commemorative portrait.

Etymology
French plaque meant a metal plate or coin. The English commemorative sense keeps the idea of a flat plate, serving as a surface for decoration or an inscription.
In context
The plaque is hard to read in places, not because the words have washed away, but because what they say is so hard to believe.