round–robin

1a :  a written petition, memorial, or protest to which the signatures are affixed in a circle so as not to indicate who signed firstb :  a statement signed by several personsc :  something (such as a letter) sent in turn to the members of a group each of whom signs and forwards it sometimes after adding comment

2 :  round table 2

3 :  a tournament in which every contestant meets every other contestant in turn

4 :  series, round