The letter "V" doesn't directly describe how things move in solids. However, there are a few concepts related to solids and motion that use "V" that might be what you're thinking of:

* Velocity (v): This describes the speed and direction of an object's motion. Solids can have velocity just like any other object.

* Vibration (v): While not represented by a single "V", the particles within solids are constantly vibrating. The amount of vibration influences a solid's properties like temperature and hardness.

* Viscosity (η): While viscosity describes the resistance to flow in liquids, it's closely related to the internal friction within a solid. Solids have a very high viscosity, meaning they resist deformation.

Could you give me more context or information about what you're looking for? For example:

* What kind of movement are you interested in? (Overall motion, internal movement, etc.)

* What kind of solid are you thinking about? (Rigid, elastic, etc.)

With more information, I can give you a more specific and accurate answer.