null and void

WordReference Random House Learner's Dictionary of American English © 2026

null /nʌl/   adj. 

1. lacking value or significance.
2. being or amounting to nothing;
   nil.
3. Mathematics (of a set)
   • empty:
     A null set is a collection that has no members in it.

Idioms

4. Idioms null and void, without force or effect;
   not valid:
   The contract is now null and void.

nul•li•ty, n. [uncountable] See -null-.

-null-, root. 

1. -null- comes from Latin, where it has the meaning "none;
   not one.'' This meaning is found in such words as: annul, null, nullify.

WordReference Random House Unabridged Dictionary of American English © 2026

null  (nul), adj. 

1. without value, effect, consequence, or significance.
2. being or amounting to nothing;
   nil;
   lacking;
   nonexistent.
3. Mathematics (of a set)
   • empty.
   • of measure zero.
4. being or amounting to zero.
5. Idioms null and void, without legal force or effect;
   not valid:
   This contract is null and void.

n. 

6. Electronics a point of minimum signal reception, as on a radio direction finder or other electronic meter.

v.t. 

7. to cancel;
   make null.

• Latin nūllus, equivalent. to n(e) not + ūllus any
• 1555–65