noun
participation slot; limit on participation
Refers to a quota or available space for participants in an event, course, or activity. Often used when registration has a cap.
このイベントは参加枠が限られているので、早めに申し込んでください。
This event has limited participation slots, so please apply early.
参加枠がすぐに埋まってしまった。
The participation slots filled up quickly.
Compound of 参加 (participation) and 枠 (frame, slot, limit).