Adverb meaning that an action or change happens swiftly or immediately (e.g., 'suddenly/quickly; immediately').
彼は急に立ち上がった。
He stood up suddenly.
急に用事ができて、出かけなければならない。
Something came up suddenly, and I have to go out.
急に声をかけられて驚いた。
I was surprised by being suddenly addressed.
Adverb meaning that something happens unexpectedly or abruptly ('suddenly/abruptly/unexpectedly').
空が暗くなり、急に雨が降り出した。
The sky darkened and it started to rain suddenly.
急に辞めると言われて困った。
I was troubled when I was suddenly told they were quitting.
彼の態度が急に変わった。
His attitude changed abruptly.
Adverb describing something becoming steep or sharp (e.g., a slope or bend that becomes steep).
この道は急に下るので気をつけてください。
Be careful; this road drops steeply.
角を曲がると、道が急に上りになる。
After turning the corner, the road suddenly goes uphill.