bound variable
nounA bound variable is a letter in a math or logic sentence that is tied to a special symbol like 'for all' or 'there exists'.
In the sentence 'for every x, x is greater than zero', the letter x is a bound variable.
OTHER MEANINGS
2. In computer programming, a variable that is connected to a value or a function parameter inside a piece of code.
The loop counter i is a bound variable inside the for loop.
3. In lambda calculus, a variable that appears in the body of a function and is tied to that function's parameter.
In the expression λx.x+1, the x is a bound variable.
4. A variable whose meaning is fixed by the expression that contains it, rather than by something outside.
The bound variable y in 'there exists y such that y squared equals 4' only makes sense inside that statement.