noun
amateur sumo wrestling
Refers to sumo wrestling practiced outside the professional sumo world, often at local festivals, schools, or as a hobby.
地元の祭りで草相撲大会が開かれた。
An amateur sumo tournament was held at the local festival.
Professional sumo wrestling, as opposed to amateur sumo (草相撲).
Compound of 草 (くさ, 'grass') and 相撲 (すもう, 'sumo'). The prefix 草- here means 'amateur' or 'informal', similar to 草野球 (くさやきゅう, 'sandlot baseball').