A sudden turn or rapid change (e.g., in weather, a patient's condition, or market prices).
昨日の夜、天候が急変して大雨が降った。
Last night the weather suddenly changed and heavy rain fell.
患者の容体が急変したので、医師を呼んだ。
The patient's condition suddenly worsened, so we called the doctor.
経済指標の発表で株価が急変した。
Stock prices changed sharply following the economic data release.
An accident or emergency that occurs suddenly; a situation requiring immediate response.
山で急変があり、救助隊が出動した。
A sudden emergency occurred on the mountain, and rescue teams were dispatched.
病院は急変に備えて夜間も医師を待機させている。
The hospital keeps doctors on standby at night to prepare for emergencies.
飛行機内で急変が起きたため、緊急着陸した。
An emergency occurred on board the plane, so it made an emergency landing.