Admin
An admin is a member with elevated permissions. Admins approve pending bookings, finalise bookings, approve submitted expenses, edit asset and billing settings, invite and manage members, and confirm or dismiss reported squawks.
Admins can do everything an owner can do except transfer ownership, delete the syndicate, and manage the paid subscription. A syndicate can have any number of admins.
Treasurer is not a separate role — it is an admin who takes on the financial workflows (finalising bookings, approving expenses, recording payments). Use “treasurer” in prose when that is what you mean.