Indeterminate (variable)

In mathematics, particularly in formal algebra, an indeterminate is a symbol that is treated as a variable, but does not stand for anything else except itself. It may be used as a placeholder in objects such as polynomials and formal power series. In particular:

• It does not designate a constant or a parameter of the problem.
• It is not an unknown that could be solved for.
• It is not a variable designating a function argument, or a variable being summed or integrated over.
• It is not any type of bound variable.
• It is just a symbol used in an entirely formal way.

When used as placeholders, a common operation is to substitute mathematical expressions (of an appropriate type) for the indeterminates.

By a common abuse of language, mathematical texts may not clearly distinguish indeterminates from ordinary variables.