What does renounce mean?

Renounce, in the context of the Oath of Allegiance, means to formally reject or give up; the new citizen renounces all prior allegiance and fidelity to any foreign prince, potentate, state, or sovereignty. The verb appears in the very first clause of the oath set out in 8 CFR section 337.1: "I hereby declare, on oath, that I absolutely and entirely renounce and abjure all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty, of whom or which I have heretofore been a subject or citizen." The two verbs renounce and abjure are paired for emphasis, both meaning to give up under oath.

The legal effect of this renunciation is that the new U.S. citizen owes primary allegiance to the United States. Whether the renunciation also terminates the applicant's citizenship in the country of origin is a matter of that country's law, not U.S. law. Some countries automatically strip citizenship when a national takes a foreign oath of allegiance; many others (including most modern Western democracies) recognize dual citizenship and do not treat the U.S. oath as a renunciation that takes effect under their law.

The U.S. position, expressed in State Department guidance and reinforced by Supreme Court decisions in Afroyim v. Rusk (1967) and Vance v. Terrazas (1980), is that dual citizenship is permitted and that the renunciation language in the U.S. oath does not by itself extinguish U.S. recognition of a person's other nationality. Practical consequences for things such as travel on a foreign passport, military service abroad, or property ownership depend on the laws of the other country.