preliminary conference; preparatory meeting
A meeting held before a main conference or negotiation to discuss agenda, strategy, or preliminary matters.
We held a preliminary conference before the main meeting to sort out the agenda.
事前協議 is a broader term for prior consultation or discussion, while 予備会議 specifically refers to a formal preliminary meeting.
Compound of 予備 (yobi, 'preliminary, reserve') and 会議 (kaigi, 'meeting, conference').