How you name your objects in your game will really depend on your game and what make sense to you and your team.
However, you seem to be after the more generic term body. What you're actually working with is called rigid body and rigid body dynamics, which imply that the objects in your simulation do not deform (or deform so little that we neglect the deformation).
- Bodies that are part of the environment and never move are often called static bodies.
- Bodies that can move when interacted with are called dynamic bodies.
- Some physics engines have a
disabled property for disabling the body and not consider it when performing a simulation step. Some have an
auto_disable flag that allows the body to disable itself when it's not moving for a period of time; these bodies are re-enabled upon a collision with another object.
I hope these details will help you come up with names that fit your game/architecture.