fluidity  
noun [ U ] uk/fluˈɪd.ə.ti/ us/fluˈɪd.ə.t̬i/
  (CHANGE)      
  易变性;不稳定性
the quality of being likely to change repeatedly and unexpectedly
  the fluidity of the political situation 政治局势的不稳定性 
   (MOVEMENT)      
  formal流畅 
the quality of being smooth and continuous
  Durante dances with fluidity and grace. 杜兰特跳起舞来动作优雅流畅。 
   (LIQUID)     
 流动性
(of a substance) the quality of being not solid and able to flow