English
firedamp
From fire + damp with 'damp' not in the usual sense of 'moist' but old German, modern Dutch, Danish 'damp' as steam or vapour, hence a gas liable to catch fire.
Today it means
noun A flammable gas (mostly methane) found in coal mines; forms an explosive mixture with air.
Language periods are conventional ranges, not dates for this word.
Etymograph / firedamp