The following diagram shows how the moon causes tides on Earth: In this diagram, you can see that the moon's gravitational force pulls on water in the oceans so that there are "bulges" in the ocean on both sides of the planet. The moon pulls water toward it, and this causes the bulge toward the moon.
Viscosity refers to the speed at which a substance can flow (i.e. the thickness of the substance/its ability to flow). I think that's the closest the English language gets.
