Answer:

NULL

Answer	Crossword Clue
NULL	Containing no matter
NULL	Void's partner
NULL	No longer valid

NULL	Without legal force
NULL	Zero
NULL	Invalid
NULL	Invalidate
NULL	.. and void
NULL	Like sets with no elements
NULL	Nonexistent
NULL	Worthless

NULL	Empty, as a math set
NULL	Having no effect
NULL	Partner of void
NULL	Amounting to nothing
NULL	No longer in force
NULL	Having no value
NULL	Without significance
NULL	Void partner

NULL	Void companion
NULL	... and void
NULL	Void's companion
NULL	Without value
NULL	No longer in effect
NULL	Without a value, as a database cell
NULL	Empty, as a set
NULL	Of no value

NULL	Of no legal force
NULL	Nothing
NULL	Lacking value
NULL	Empty
NULL	Empty, in math
NULL	Not valid
NULL	Valueless
NULL	Voided

NULL	.. and void (inoperative)
NULL	Having no elements
NULL	Having no force
NULL	Like the set Ø
NULL	Of no legal force.