spontaneous

/spɑnˈteɪniəs/

happening or arising without apparent external cause

中文释义：自发的；自然的；无意识的

The audience gave a spontaneous round of applause after the speech.

演讲结束后，观众自发地鼓起掌来。

Spontaneous laughter filled the room when the comedian told a joke.

喜剧演员讲了个笑话，房间里充满了自然的笑声。