A fire maintained during the night by people keeping watch(noun)
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Use "watchfire" in a sentence
"In less than a second Lord Crawford was at their head, and, dispatching an Archer to alarm the King and his household, drew back his little party to some distance behind their watchfire, that they might not be seen by its light."
"She was arrested Feb. 9, 1919, and served five days in District Jail for participating in watchfire demonstration."
"As the watchfire blazed up, its gleam fell upon masses of honeysuckle and woodbine, on white, mouldering walls beneath, and dark, waving trees above; while the group of mountaineers who gathered round its light, with their long beards and vivid dresses, completed the strange picture."