An integral expressed as the difference between the values of the integral at specified upper and lower limits of the independent variable.

i.e.,

The definite integral of f(x) between a and b represents the area under the curve y = f(x), above the x-axis to the right of the line x = a, and to the left of the line x = b. The definite integral of f(x) = F(b)-F(a) where F is an anti-derivative function for f(x).