board chairman; managing director; chief director
The top executive of an organization's board, such as a school foundation, hospital, or non-profit. In some contexts, may be translated as 'president' or 'chairperson'.
He assumed the position of board chairman of the educational foundation.
The managing director convened the meeting.
理事長 is the director general of a foundation, hospital, or nonprofit board, while 総裁 is used for higher-profile institutions like political parties or central banks.
Compound of 理事 (director, board member) and 長 (head, chief).