1To boil or become hot enough to bubble (e.g., water boiling).
やかんの水が沸いているから火を止めてください。
The kettle's water is boiling, so please turn off the heat.
鍋が沸くまで弱火で待つ。
Wait on low heat until the pot begins to boil.
2To become excited or to erupt (in applause, cheering); to be in a ferment; for an event to be lively.
会場は歌手の登場で大いに沸いた。
The venue erupted when the singer appeared.
新製品の発表で社内が沸いている。
The company is buzzing with excitement over the new product announcement.
3To ferment (to bubble or froth due to fermentation).
この果汁は温度が高いと早く沸いてしまうことがある。
This juice can ferment quickly if the temperature is high.
4To melt (of metals)—to become molten due to high heat.
高熱で鉄が沸き、形が崩れた。
The iron melted under intense heat and lost its shape.