A Null

1. A non-existent or empty value or set of values.
2. Zero quantity of expressions; nothing.
3. Something that has no force or meaning.
4. (computing) the ASCII or Unicode character (␀), represented by a zero value, that indicates no character and is sometimes used as a string terminator.
5. (computing) the attribute of an entity that has no valid value.
6. One of the beads in nulled work.
7. (statistics) Null hypothesis.