caprice

caprice
/kəˈpri:s; kə`pris/ n
1
(a) [C] sudden change in attitude or behaviour with no obvious cause; whim 态度或行为无明显缘故的突然改变; 突如其来的念头.
(b) [U] tendency to such changes 有上述突然改变的倾向.
2 [C] short lively piece of music in an irregular style 短小的随想曲.

牛津英汉双解词典