Definition of null-space:
(n) :
A non-existent or empty value or set of values.
(n) :
Zero quantity of expressions; nothing.
(n) :
(computing) The attribute of an entity that has no valid value.
(n) :
(computing) The null character; the ASCII or Unicode character (␀), represented by a zero value, which indicates no character and is sometimes used as a string terminator.
(adj) :
Having no validity; "null and void".
(n) :
Something that has no force or meaning.