An occurrence of a variable in a logic formula which is not inside the scope of a quantifier.
Free Variable
See also
Bound, Quantifier, SentenceExplore with Wolfram|Alpha
References
Curry, H. B. Foundations of Mathematical Logic. New York: Dover, p. 112, 1977.Referenced on Wolfram|Alpha
Free VariableCite this as:
Weisstein, Eric W. "Free Variable." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/FreeVariable.html