Meaning

noun (computer science) rules determining the format and transmission of data

noun forms of ceremony and etiquette observed by diplomats and heads of state

noun code of correct conduct

originBorrowed from Middle French protocolle, protocole (“document, record”), from Late Latin protocollum (“the first sheet of a volume (on which contents and errata were written)”), from Byzantine Greek πρωτόκολλον (prōtókollon, “first sheet glued onto a manuscript”), from πρῶτος (prôtos, “first”) + κόλλα (kólla, “glue”).

Etymology from Wiktionary, CC BY-SA 3.0