niche  
noun [ C ] uk/niːʃ/ us/nɪtʃ/
  (POSITION)         
  (尤指本人合意的)适合的工作(或职位);称心的工作
a job or position that is very suitable for someone, especially one that they like
  He has carved/made a niche for himself as a financial advisor. 他成为了财务顾问,为自己找到了合适的发展方向。 
  合宜的小环境
an area or position that is exactly suitable for a small group of the same type
  an ecological niche 生态龛 
   (HOLLOW)     
 (尤指用来放置塑像的)壁龛
a hollow in a wall, especially one made to put a statue (= artistic object) in so that it can be seen