In mathematics, a coefficient is a number or symbol that is multiplied by a variable of a single term or the terms of a polynomial. It is usually an integer that is written next to the variable, and variables without a number are assumed to have a coefficient of 1. For example, in the term 2x, 2 is the coefficient, and in the term y, 1 is the coefficient. Coefficients can be positive or negative, real or imaginary, or in the form of decimals or fractions.

A term can be a number, a variable, the product of two or more variables, or the product of a number and a variable. An algebraic expression is formed by a single term or by a group of terms. A factor is one part of a product, and a coefficient is a number that is multiplied by the variable.

In summary, a coefficient is a numerical factor of a term containing constants and variables. It is a number or symbol that is multiplied by a variable of a single term or the terms of a polynomial.