sigilli

Sigilli is the plural of sigillo, an object or mark used to authenticate, secure, or certify a document, container, or object by leaving an impression or symbol. The term derives from Latin sigillum, a diminutive of signum, meaning mark or sign.

Historically, seals have played a central role in administration and diplomacy. In ancient and medieval times, rulers, officials, merchants, and individuals used signet rings or seal matrices to press an emblem into soft materials such as wax, clay, or lead. A seal on a document signified authenticity, consent, or authority, while breaking or removing a seal could indicate tampering or repudiation. Seals were also attached to containers and packages to guarantee integrity during transit, serving as tamper-evident closures.

Modern usage includes official and organizational seals used to certify, authorize, or validate documents and archival materials. In many jurisdictions, physical or electronic seals symbolize legitimate authority or authenticity. Seals also appear in practical applications for packaging, bottles, and shipping containers to deter tampering or theft. In engineering and industry, the term seal refers to a device that prevents leakage in joints, valves, or machinery, ensuring containment and function.

In the digital age, the concept persists in security practices, with the notion of digital seals or signatures providing authentication and integrity for electronic documents and software releases. These digital equivalents are typically referred to as electronic signatures or certificates, but the idea of a seal as a mark of trust remains central.