round robin
noun [ C ] uk/ˌraʊnd ˈrɒb.ɪn/ us/ˌraʊnd ˈrɑː.bɪn/
(LETTER)
UK（通常指提出请求或投诉的）联名信，联名声明书
a letter, usually of demands or complaints, that is signed by many people
UK传阅的信件，发送给多人看的信件（如在圣诞节时的信件，告诉别人自己那一年所做的事情）
a letter that you send to a lot of people, for example at Christmas, telling them what you have done that year
(COMPETITION)
循环赛
a competition in which all the players play against each other at least once