special event; event
Refers to a planned occasion such as a fair, exhibition, festival, or promotional gathering. Often used in commercial or organizational contexts.
A Hokkaido product fair is being held at the department store.
I hear there will be a big event in front of the station next month.
event hall; exhibition hall; function room
Compound of 催 (さい, 'to hold an event') and 事 (じ, 'matter, thing'). The exact historical derivation is uncertain, but the word is conventionally associated with planned gatherings.