下火
したび · shitabi · JLPT N1 · noun
low
下 — horizontal line 一 + mark below
下 is an indicative character: a long horizontal line represents a reference level, and a shorter stroke placed beneath it points to the area below. The original meaning 'below, down' comes directly from this spatial diagram, and it later extended to verbs like 'descend' and 'lower'.
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.