happening in a natural way without being planned or thought about 自然发生的；一时冲动的；自发的 | spontaneous applause/cheers 自发的鼓掌/欢呼 |
| He was suddenly filled with tears of spontaneous emotion. 他突然激动得热泪盈眶。 |
| | a | used in a positive way about someone who often behaves in a natural and friendly way , without worrying about what they say or do 自然的；天真直率的 | | Elsie’ s one of the most spontaneous, fun-loving people I know. 埃尔西是我所认识的最天真率直、爱开玩笑的人之一。 | |
| | b | used about chemical or biological changes or processes that happen suddenly in a natural way （化学或生物变化或过程）自发的，非外力诱发的 | | spontaneous wildfires 自燃的野火 | | spontaneous contractions of the muscles in the oesophagus 食管肌肉的自动收缩 | |