obsolete sumo rule prohibiting matches between wrestlers from the same group of stables
Historical sumo term; refers to a now-abolished rule that prevented wrestlers belonging to the same ichimon (group of stables) from facing each other in tournaments.
In the past, there was a system called ichimon-betsu sōatari, and wrestlers from the same ichimon did not face each other.
Compound of 一門 (ichimon, 'one group of stables'), 別 (betsu, 'separate'), and 総当り (sōatari, 'round-robin'). The term describes a round-robin tournament format separated by stable groups.