noun
irregular days off; no fixed closing days; no set holidays
Describes a business or workplace where days off are not on a fixed weekly schedule, or a shop that closes irregularly rather than on a set weekday.
この店は不定休なので、行く前に電話で確認したほうがいい。
This shop has irregular closing days, so you should call ahead before going.
彼の仕事は不定休で、週末に休めるとは限らない。
His job has no fixed days off, so he can't always rest on weekends.