differential operator,
n. 1. the operator del used in vector analysis and defined as
where i, j, k are unit vectors in the direction of the x-, y-, and z-axes, respectively, and ∂/∂x, ∂/∂y, and ∂/∂z are the respective partial derivatives of the given function of x, y and z. See also gradient, divergence, curl, Laplace operator.
2. any operator involving derivatives.