(mathematics) A type of average calculated as the arithmetic mean of the squares of the values divided by the arithmetic mean of the values, ie. C=(x_1²+x_2²+...+x_n²)/n/(x_1+x_2+...+x_n)/norC(x_1,x_2,...,x_n)=x_1²+x_2²+...+x_n²/x_1+x_2+...+x_n

plural of contraharmonic mean