IPA: //ˈfaɪərˌfaɪtə//
KK: /ˈfaɪərˌfaɪtər/
A person who is trained to put out fires and rescue people from dangerous situations involving fire.
The firefighter bravely entered the burning building to save the trapped residents.
Firefighter → It is formed from "fire" (from Old English "fyr", meaning flame or combustion) and "fighter" (from Old English "feohtan", meaning to fight). The word "firefighter" refers to a person who fights against flames or fire.
Think of someone who is fighting against flames — 'fire' represents the flames, and 'fighter' means a person who fights.