English 'diploma' comes through Latin from Greek 'díplōma' (a folded document), from 'diplóos' (double, twofold) — originally describing the physical form of an official document folded in half, which became the standard term for any document conferring privilege, and eventually for the certificate marking academic completion.
An official document issued by an educational institution certifying that the holder has completed a course of study.
From Latin 'diplōma' (official document, state letter), from Greek 'díplōma' (δίπλωμα, a folded document, a letter of recommendation), from 'diplóos' (δίπλοος, double, twofold), from 'di-' (two) + 'ploûs' (fold, related to 'plekein,' to fold). The word originally referred to any official document that was folded in two — a physical description that became the standard term for documents conferring privilege. Roman 'diplomata' were metal tablets granting citizenship or discharge to soldiers. Key
The word 'diplomacy' — the art of international relations — derives directly from 'diploma.' In the seventeenth century, international treaties and credentials were called 'diplomata' (the Latin plural of 'diploma'), and the people who handled them were 'diplomats.' The study of old documents and charters was called 'diplomatics.' Thus the diplomat, the academic graduate, and the archivist are all connected by the same folded piece of paper.