(statistics) A hypothesis set up to be nullified or refuted in order to support an alternative hypothesis. When used, the null hypothesis is presumed true until statistical evidence in the form of a hypothesis test indicates otherwise. Therefore, the null and the alternative hypothesis must be mutually exclusive and exhaustive.

In a closed space-time, especially for an Einstein cylinder, null infinity for a given point is the limit of convergence of the light cone most distant from the given point. That is, it is the limit of a set of points that each have a time-like separation from every point that has a space-like separation from the given point.

(idiomatic, law) invalid, cancelled, unenforceable

(linguistics) An implied (but omitted) anaphora.

plural of null object

ornamental turned work resembling beads strung on a rod

(category theory) An object that is both an initial and terminal object. / (object-oriented programming) An object that does nothing and is used instead of using a null.

plural of null set

plural of null morpheme

plural of null result