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1. Having no legal force; invalid: render a contract null and void.
2. Of no consequence, effect, or value; insignificant.
3. Amounting to nothing; absent or nonexistent: a null result.
4. Mathematics Of or relating to a set having no members or to zero magnitude.
tr.v. nulled, null·ing, nulls
To make null.
1. Zero; nothing.
2. An instrument reading of zero.

[French nul, from Old French, from Latin nūllus; see ne in Indo-European roots.]