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Webster 1913 Edition

Noun.

A chimney board or screen to close a fireplace when not in use.

fireboard ‎(plural fireboards)

A chimney board or screen to close a fireplace when not in use.
- 1851, Herman Melville, Moby Dick, chapter 3
  I then glanced round the room; and besides the bedstead and centre table, could see no other furniture belonging to the place, but a rude shelf, the four walls, and a papered fireboard representing a man striking a whale.