An expression in mathematics which does not have meaning and so which is not assigned an interpretation. For example, division by zero is undefined in the field of real numbers.

# Undefined

## See also

Ambiguous, Complex Infinity, Directed Infinity, Division by Zero, Ill-Defined, Indeterminate, Well-Defined## Explore with Wolfram|Alpha

## Cite this as:

Weisstein, Eric W. "Undefined." From *MathWorld*--A Wolfram Web Resource. https://mathworld.wolfram.com/Undefined.html