A more thorough explanation:

Definition: Compos sui (kom-pəs s[y]oo-I) is a Latin term that means "master of one's self." It refers to a person who has control over their own body and movements.

Example: A martial artist who has trained for years to have complete control over their body is an example of someone who is compos sui. They are able to move their limbs with precision and accuracy, and can execute complex techniques with ease.

Explanation: The example illustrates the definition of compos sui because the martial artist has achieved a level of mastery over their body that allows them to move with intention and control. They are not at the mercy of their limbs, but rather have the power to direct them as they see fit. This level of self-mastery is what defines someone as compos sui.