1. the ornamental structure that frames a fireplace opening, typically including a mantel and surround
Usage: also called mantelpiece or mantel; common in British English
2. a shelf above a fireplace, used for displaying decorative objects
Usage: often used interchangeably with mantel shelf

Examples

• The chimneypiece was decorated with candles and family photographs.
• She hung a mirror above the chimneypiece to reflect light into the room.
• The Victorian chimneypiece featured intricate marble carvings.
• They placed holiday stockings along the chimneypiece.
• The antique chimneypiece was one of the most valuable features of the old house.
• A vase of flowers sat on the chimneypiece in the living room.