the expectation or mean value of the variable formed by multiplying the differences obtained by subtracting two given variates from their respective means; the product of the standard deviations of two given variates and the coefficient of correlation between them.

statisticsa measure of the association between two random variables, equal to the expected value of the product of the deviations from the mean of the two variables, and estimated by the sum of products of deviations from the sample mean for associated values of the two variables, divided by the number of sample points. Written as Cov (X, Y)