Viscous force

Definition

The viscous force is the force between a body and a fluid (liquid or gas) moving past it, in a direction so as to oppose the flow of the fluid past the object. In particular, the force acts on the object in the direction in which the fluid is moving relative to it (and hence, opposite to the direction in which it is moving relative to the fluid).

Viscous force is an analogue in fluids of the force of friction.