"His door isn't entirely closed."

Translation: Jeho dveře nejsou úplně zavřené.

[Ovenist]

Door is always plural or is "nejsou" a mistake?

[deactivated user]

It's always plural.

[BrianSille2]

'Entirely' would not be used in this context in standard English. 'Completely' would be better although 'fully closed' would be more usual.