transition          
 noun [ C or U ] uk/trænˈzɪʃ.ən/ us/trænˈzɪʃ.ən/
C2 转变;过渡
a change from one form or type to another, or the process by which this happens
  The health-care system is in transition at the moment. 医疗保健制度目前正在变革中。 
 There will be an interim government to oversee the transition to democracy. 将会有一个临时政府来监督向民主政治的过渡。 
  性别转换
a change in which someone starts living their life as a person of a different gender
  She began her transition from male to female almost seven years ago. 大约七年前,她开始了从男性到女性的转变。 
 - More examples
 - The transition from a totalitarian state to a free country will be long and slow.
 - The transition from boyhood to manhood can be a confusing period.
 - There will be a transition period before Jenny takes over as boss.
 
transition       
verb [ I or T ] /trænˈzɪʃ.ən/
 转换性别
to start living as a person of a different gender
  Bornstein transitioned from male to female almost 20 years ago. 大约20年前,伯恩斯坦从男人变成了女人。 
 It wasn't easy transitioning gender in the military. 在军队中转换性别并不容易。