expression, suru verb (irregular)
break up a meeting; call it a night
Polite, euphemistic expression used to end a social gathering, party, or meeting. Often used by the host or organizer.
そろそろお開きにしましょうか。
Shall we call it a night soon?
会議を予定より早くお開きにした。
We ended the meeting earlier than planned.
Derived from the verb 開く (ひらく, to open), with the honorific prefix お and the verb する. The use of 'open' to mean 'end' is a euphemism, possibly from the idea of opening the door to leave or opening up the gathering to disperse.