not open [= shut; ≠ open]:
Make sure all the windows are closed.
She kept her eyes tightly closed.
2 [not before noun]
if a shop, public building etc is closed, it is not open and people cannot enter or use it [= shut; ≠ open]:
The shops here are closed on Sundays.
closed to the public/visitors etc
The castle is closed to visitors in winter.
restricted to a particular group of people [≠ open]:
The golf club has closed membership.
The police have a closed circle of suspects.
not willing to accept new ideas or influences [≠ open]:
You're facing this situation with a closed mind.
closed society/world/way of life
Venetian art in this period was a closed world.
if something happens behind closed doors, it happens in private and the public are not allowed in:
It seems that the deal was made behind closed doors.
Football authorities ordered the club to play its next two games behind closed doors after the riots in February.
a subject or problem that someone does not know about or understand:
Mathematics has always been a closed book to me.