A coefficient is a numerical or constant factor that multiplies a variable in a term of an algebraic expression or equation. For example, in the term $5x^2$, 5 is the coefficient.
Polynomial: An algebraic expression consisting of terms which are sums and/or differences of variables raised to non-negative integer powers and multiplied by coefficients.
Leading Coefficient: The coefficient of the term with the highest degree in a polynomial.
Zero of a Polynomial: A value for which a given polynomial evaluates to zero; also known as root or solution.