say it: FAHY-ur-damp
firedamp is a noun meaning "a mixture of gases (mostly methane) that form in coal mines and become explosive when mixed with air". It carries one recorded sense.
a mixture of gases (mostly methane) that form in coal mines and become explosive when mixed with air
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for firedamp come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.