A more thorough explanation:

Definition: Possess means to own, occupy, physically hold, or have under one’s complete control.

For example, in the context of controlled substances, a person possesses a controlled substance when they know what it is, know it's there, and have control over it. In the context of property, to possess a property means to use or occupy it, and the hallmark of control is the ability to admit or exclude others from the property. In criminal statutes, possess normally signifies intentional control of a designated thing accompanied by knowledge of its character.

Overall, possessing something means having complete control over it, whether it's a physical object or a controlled substance.