禍

A phono-semantic compound composed of:

示 — semantic component related to spirits, gods, or fate; 咼 — phonetic component indicating the sound (화 / huò). The character reflects the idea of misfortune believed to come from divine or unseen forces, which later generalized to mean disaster or calamity.
Semantic development: - misfortune attributed to divine forces; - disaster or calamity; - cause of trouble or harm.

재화 (災禍) — disaster; calamity

화근 (禍根) — root of disaster; cause of trouble

전화위복 (轉禍爲福) — “turn disaster into blessing”

禍 is often paired with 福 (fortune) to express contrast (e.g., 禍福). The character carries a strong nuance of serious or fateful misfortune, not just minor trouble.
Related characters: 災 — disaster

厄 — misfortune

福 — blessing (often contrasted with 禍)