a vector perpendicular to each of two given vectors u and v and having magnitude equal to the product of the magnitudes of u and v and the sine of the angle from u to v
See vector product in American Heritage Dictionary 4
A vector c, depending on two other vectors a and b, whose magnitude is the product of the magnitude of a, the magnitude of b, and the sine of the angle between a and b. Its direction is perpendicular to the plane through a and b and oriented so that a right-handed rotation about it carries a into b through an angle not greater than 180°. The notation for c is c = a × b. Also called cross product.