Step 1: Define the Latin term ultra vires.
Ultra vires is a Latin legal maxim meaning "beyond powers." It describes an act performed by a body (such as a company, government authority, or statutory body) that exceeds the scope of powers granted to it by law or its constitution.
Step 2: Contrast with intra vires.
The opposite term, intra vires, means "within powers." An ultra vires act is void and unenforceable because the actor lacked the legal authority to perform it.
Step 3: Select the correct meaning.
Ultra vires means beyond powers, not illegal activities, custodial death, or within powers.
\[ \boxed{\text{Beyond powers}} \]