A cast iron plate at the back of a fireplace that reflects heat and protects the masonry; also a type of colorful Asian pheasant.
From 'fire' + 'back' (rear surface). Architectural and ornithological term.
Medieval fireplaces were terribly inefficient until someone realized that a metal plate in back could bounce heat forward—it's like adding a mirror to warmth, and it made winters actually survivable.
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