Coefficient (noun)

1. A numerical or quantitative factor that determines the rate, degree, or amount of a particular phenomenon or effect.
2. A number or constant that represents the relationship between two variables in an equation or mathematical expression.
3. A measure of the degree of association between two variables.

Origin:

Late 17th century: from french coefficient, from latin coeficient- "making up a whole", from co- "together" + efficere "accomplish".

Examples:

1. The coefficient of friction between the two surfaces was measured.
2. The coefficient in the equation determines the steepness of the line.
3. The thermal conductivity coefficient determines the heat transfer rate.
4. The regression analysis revealed a high coefficient of determination.
5. The coefficient of expansion is used to determine the change in length of a material with temperature.