From The Collaborative International Dictionary of English v.0.48 [gcide]:
firedamp \firedamp\ n. a mixture of gases (mostly methane) that forms in coal mines and becomes explosive when mixed with air. It is a source of serious hazard in coal mining operations. [WordNet 1.5 +PJC]
From WordNet (r) 3.0 (2006) [wn]:
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