A familiar and respectful term for a leader or boss, often used within a group to refer to the person in charge. Carries a slightly old-fashioned or jocular tone.
Let's get the venue ready before the boss arrives.
彼はチームの御大としてみんなから慕われている。
He is well-liked by everyone as the head of the team.
An abbreviation of 御大将 “commander; leader,” used as a respectful or jocular term for the chief figure of a group.