An expression is ambiguous if its definition permits more than one interpretation or value. Ambiguity is one way an expression can be ill-defined.
Ambiguous
See also
Ill-Defined, Well-DefinedExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Ambiguous." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Ambiguous.html