null

UK: /ˈnʌl/ US: /nʌl/ ,(nul)

WordReference Random House Learner's Dictionary of American English © 2025

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 © 2025

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

Collins Concise English Dictionary © HarperCollins Publishers::

null / nʌl/ adjective

1. without legal force; invalid; (esp in the phrase null and void)
2. without value or consequence; useless
3. lacking distinction; characterless
4. nonexistent; amounting to nothing
5. quantitatively zero
6. relating to zero
7. (of a set) having no members
8. involving measurement in which an instrument has a zero reading, as with a Wheatstone bridge

Etymology: 16th Century: from Latin nullus none, from ne not + ullus any