free variable

noun

UK /friː ˈveəriəbl/

US /friː ˈveriəbl/

A free variable is a letter in a math sentence that can stand for any number.

In the equation x + 3 = 7, the letter x is a free variable.

SYNONYMS

unbound variable open variable placeholder unknown

RELATED WORDS

bound variable variable equation algebra expression

OTHER MEANINGS

2. In logic, a variable not tied to a quantifier such as 'all' or 'some'.

In 'x is happy', x is a free variable because nothing says who x is.

3. In computer programming, a variable used in a function that is not defined inside that function.

The function reads a free variable from the surrounding code.

4. A symbol in a formula that is not fixed to a specific value.

The formula has one free variable, so its value can change.