[¦sen·trəl ¦mēn ′äp·ə‚rād·ər] (mathematics) A difference operator, denoteed μ, defined by the equation μƒ(x) = [ƒ(x + h /2) + ƒ(x-h /2)]/2, where h is a constant denoting the difference between successive points of interpolation or calculation. Also known as averaging operator.