火災
かさい · kasai · JLPT N3 · noun
fire
🔥🏠 火災 = fire + disaster: a fire that becomes a calamity
火 (ka) is fire and 災 (sai) is disaster, as in 災害 saigai, calamity. Together they mean a fire that does real damage, like a building or house fire. The word is a set phrase that shows up in fire alarms (火災報知器) and on fire insurance (火災保険).
火 — pictograph of flames rising
火 is a pictograph showing flames rising upward from a fire, with the central stroke as the main blaze and the side strokes as sparks. The ancient oracle bone form looked even more clearly like a burning flame. It still means 'fire' today and serves as a common radical in characters related to heat, burning, or cooking.