From Wikipedia - https://en.wikipedia.org/wiki/Couple_(mechanics)
In mechanics, a couple refers to two parallel forces that are equal in magnitude, opposite in direction and do not share a line of action.
A better term is force couple or pure moment. Its effect is to create rotation without translation or, more generally, without any acceleration of the centre of mass. In rigid body mechanics, force couples are free vectors, meaning their effects on a body are independent of torque. This is not to be confused with the term torque as it is used in physics, where it is merely a synonym of moment. Instead, torque is a special case of moment.