A board or surface designed to reflect or direct flares; possibly a nautical signaling device or specialized equipment used in conjunction with flare signals.
Compound of 'flare' (a bright light signal) and 'board' (a flat surface). The term appears to be specialized nautical or military terminology for signal management.
Flareboards and similar signal devices represent pre-electronic communication—sailors used reflective surfaces and bright signals to communicate across distances long before radios became standard on ships.
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