Definitionen
1.NounSomeone (especially male) who is skilled in the work of fighting fire.
2.NounA person (originally a man) who keeps the fire going underneath a steam boiler (originally, shoveling coal by hand), particularly on a railroad locomotive or steamship."The fireman's job was about to get very interesting; they had just run out of coal!"
3.NounAn assistant on any locomotive, whether steam-powered or not.
4.NounA relief pitcher (reflecting the figurative analogy of rescuing the situation).
5.NounA safety inspector in coal mines.