Which term describes the act of revoking something formally?

The term that most accurately describes the act of revoking something formally is "abrogate." This word specifically refers to the formal annulment or repeal of a law, agreement, or custom, often through an official or authoritative act. It implies a significant, legal, or procedural decision that nullifies previously established rules or agreements.

While "revoke" also means to take back or withdraw something, it does not carry the same formal connotation that "abrogate" does. "Annul" is similar in meaning to "abrogate" but is usually more associated with invalidating contracts or marriage rather than laws or broader agreements. "Abjure," on the other hand, means to reject or renounce something, usually involving a stance or belief rather than a formal revocation of a law or agreement. Therefore, "abrogate" is the most precise term for referring to the formal act of revoking something.