To organize, sponsor, or host an event or gathering; also refers to the sponsor or organizer. Often used as '主催する'.
大学が国際会議を主催する予定だ。
The university plans to host an international conference.
主催者は参加人数の増加に対応して会場を変更した。
The organizers changed the venue to accommodate the increased number of participants.
市が毎年主催する祭りは地域の風物詩だ。
The festival the city hosts every year is a local tradition.