What's the noun for closeability? Here's the word you're looking for.
closure
An event or occurrence that signifies an ending.
A feeling of completeness; the experience of an emotional conclusion, usually to a difficult period.
A device to facilitate temporary and repeatable opening and closing.
(programming) An abstraction that represents a function within an environment, a context consisting of the variables that are both bound at a particular time during the execution of the program and that are within the function's scope.