[clo.sure] n [ME, fr. MF, fr. L clausura, fr. clausus, pp. of claudere to close--more at close] (14c) 1 archaic: means of enclosing: enclosure
2: an act of closing: the condition of being closed "~ of the eyelids"
3: something that closes "pocket with zipper ~"
4. [trans. of F cloture]: cloture
5: the property that a number system or a set has when it is mathematically closed under an operation
6: a set that contains a given set together with all the limit points of the given set