wilfulness       
noun [ U ] UK disapproving (US usually willfulness) uk/ˈwɪl.fəl.nəs/ us/ˈwɪl.fəl.nəs/
 任性
the quality of being wilful (= determined to do as you want)
  She was ashamed of her past wilfulness. 她为自己过去的任性感到羞愧。 
 Her large brown eyes were intelligent and full of wilfulness and energy. 她那双棕色的大眼睛充满智慧、倔强和活力。 
 See: wilful
 - More examples
 - There is a recklessness and a wilfulness in these men which is going to destroy the Party.
 - He was noted for his wilfulness and determination.
 - Does his wilfulness undermine his relationships with coaches?