Negation sign

A horizontal bar with a short downward tick at its right end, denoting logical not.

Also known as: Not sign, Backwards L, Line with a hook

MathematicalScientificStandard profile

Meanings

¬ denotes logical negation: it reverses the truth of the statement that follows. Several other notations compete with it — a tilde, a bar over the expression, an exclamation mark in programming — and none has displaced the others.

Officially standardisedVerified fact
Is encoded as U+00AC NOT SIGN, in the Latin-1 Supplement block rather than among the mathematical operators.
Contexts: Mathematics
Common modern usageVerified fact
Denotes negation: the statement it precedes is asserted to be false.
Contexts: Mathematics
Common modern usageVerified fact
Competes with several other notations for the same operation — a tilde before the statement, a bar drawn over it, and an exclamation mark in most programming languages — none of which has displaced the others.
Contexts: Mathematics

Visual description

A horizontal bar drawn at mid-height with a short vertical stroke descending from its right-hand end, forming a reversed and rotated L.

Symmetry: none
Orientation: upright

Confidence

IdentityHigh confidence: High confidence because the identity is defined by a current official standard, but multiple independent sources agree.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but multiple independent sources agree, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard, but multiple independent sources agree.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references, but multiple independent sources agree.

Sources

Unicode Code Chart: Latin-1 Supplement (U+0080–U+00FF)
The Unicode Consortium · retrieved 2026-07-30
Authoritative for the character's code point, name and block only. Unicode assigns identity; it does not define what a symbol means in use.
Glossary of mathematical symbols
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the notation means in ordinary mathematical practice and for attribution of its introduction, not for a claim that any body defines it.
Logical connective
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the notation means in ordinary mathematical practice and for attribution of its introduction, not for a claim that any body defines it.
Unicode Code Chart: Mathematical Operators (U+2200–U+22FF)
The Unicode Consortium · retrieved 2026-07-30
Authoritative for the character's code point, name and block only. Unicode assigns identity; it does not define what a symbol means in use.

Last reviewed 2026-08-01

Part of

Set theory and logic notation

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Meanings

Officially standardisedVerified fact

Is encoded as U+00AC NOT SIGN, in the Latin-1 Supplement block rather than among the mathematical operators.

Contexts: Mathematics

Common modern usageVerified fact

Denotes negation: the statement it precedes is asserted to be false.

Contexts: Mathematics

Common modern usageVerified fact

Competes with several other notations for the same operation — a tilde before the statement, a bar drawn over it, and an exclamation mark in most programming languages — none of which has displaced the others.

Contexts: Mathematics

Confidence

IdentityHigh confidence: High confidence because the identity is defined by a current official standard, but multiple independent sources agree.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but multiple independent sources agree, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard, but multiple independent sources agree.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references, but multiple independent sources agree.

Sources

Unicode Code Chart: Latin-1 Supplement (U+0080–U+00FF)
The Unicode Consortium · retrieved 2026-07-30
Authoritative for the character's code point, name and block only. Unicode assigns identity; it does not define what a symbol means in use.
Glossary of mathematical symbols
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the notation means in ordinary mathematical practice and for attribution of its introduction, not for a claim that any body defines it.
Logical connective
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the notation means in ordinary mathematical practice and for attribution of its introduction, not for a claim that any body defines it.
Unicode Code Chart: Mathematical Operators (U+2200–U+22FF)
The Unicode Consortium · retrieved 2026-07-30
Authoritative for the character's code point, name and block only. Unicode assigns identity; it does not define what a symbol means in use.

Last reviewed 2026-08-01