chairman of the board of directors
Refers to the top position in a company's board of directors, often a senior figure with significant influence.
He assumed the position of chairman of the board of directors.
The chairman of the board gave a speech at the shareholders' meeting.
社長 is the company president, responsible for day-to-day operations, while 取締役会長 is the chairman of the board, a more senior but often less hands-on role.
会長 is a general term for chairman, used in various organizations, whereas 取締役会長 specifically refers to the chairman of a board of directors in a company.
Compound of 取締役 (director, board member) and 会長 (chairman). The term is a straightforward business title.