quadrennial
adjective uk/kwɒdˈren.i.əl/ us/kwɑːdˈren.i.əl/
每四年一次的，四年一度的
happening every four years
The Olympic Games is a quadrennial gathering of athletes from around the world. 奥运会是全世界运动员四年一度的聚会。
In 2016, America indulged in the quadrennial ritual of electing a president. 2016年，美国正处于四年一度的总统选举中。