noun
attached to a particular theater; working exclusively for a theater
Describes a performer, playwright, or staff member who is permanently affiliated with a specific theater, as opposed to freelancing. Often used in historical or traditional theater contexts.
彼はその劇場の座付き作家として長年活動している。
He has worked for many years as the playwright attached to that theater.
座付きの俳優は、他の劇団の公演にはあまり出ない。
Actors attached to a theater rarely appear in productions by other troupes.
専属 is a more general term for being exclusively contracted to any organization, while 座付き specifically refers to affiliation with a theater.
Compound of 座 (za, 'theater; troupe') and 付き (tsuki, 'attached to'). The reading ざつき is a rendaku form.