polyandry        
noun [ U ] uk/ˌpɒl.iˈæn.dri/ us/ˌpɑː.liˈæn.dri/
 social science specialized一妻多夫(制) 
the practice of having more than one husband or permanent male sexual partner at the same time
  biology specialized(动物)一雌多雄 
the practice of a female animal having more than one male mate (= sexual partner)
 Compare: polygyny
See also: polygamy