What term describes an official mark or emblem used to authenticate documents?

The correct term for an official mark or emblem used to authenticate documents is "Official Seal." This term refers specifically to a device or emblem that is often used to signify authenticity or approval. Official seals are typically affixed to important documents, such as legal papers, contracts, and certifications, to ensure their legitimacy and to indicate that they carry the authority of the issuing body.

An official seal may contain distinctive features, such as the name of the issuing institution, the date, and other identifying information, which serve to validate the document it accompanies. The presence of an official seal can also help prevent fraud, as it is usually difficult to replicate accurately.

In contrast, while an official stamp and a certification mark might serve similar purposes in certain contexts, they do not inherently carry the same legal weight or formal authentication as an official seal does. A notary signature specifically refers to a notary public's written verification of a person's identity and the signing of a document, but it must be accompanied by a stamp or seal to have full legal effect. Therefore, "Official Seal" is the most precise term describing the emblem used to authenticate documents.