Other forms: firemen
A fireman on a steam engine is the one who shovels the coal. Not the one who puts fires out — the one who keeps this one burning.
On a locomotive the crew is two: the driver at the controls and the fireman feeding the firebox and watching the water. It is heavy, skilled work, and the fireman was traditionally the driver's apprentice. The word also means a firefighter, and that is the sense most people meet first, though firefighter has largely replaced it because the job was never only for men. Steam railways keep the older meaning alive.
Middle English
fyr
English
fire
English, today
fireman
From fire + -man. fire comes from Middle English fyr. From Middle English fyr, from Old English fȳr (“fire”), from Proto-West Germanic fuir, from fuïr, a regularised form of Proto-Germanic fōr (“fire”), ultimately from Proto-Indo-European péh₂wr̥. 2
Etymology from Wiktionary, CC BY-SA