returning; giving back; repaying (often something received from an authority, like a license or benefit)

💡 ポイント (Nuance)： Refers to formally returning something (money, goods, documents, etc.) to the original owner or to an official body, often because it was received by mistake, is no longer valid, or is required to be returned. 「免許の返納」「給付金の返納」のように使われる。