superior; supervisor; head of one's department
Refers to the person in charge of the organizational unit one belongs to, such as a department head or section chief. Common in workplace and bureaucratic contexts.
The application form requires the seal of your department head.
I'll decide after consulting my supervisor.
部長 is a specific title for a department manager, whereas 所属長 is a functional term for the head of whatever unit one is assigned to, which could be a section, department, or other group.
Compound of 所属 (shozoku, 'affiliation' or 'belonging to') and 長 (chō, 'head' or 'chief').