/ ˈprəʊtəkɒl; NAmE ˈproʊtəkɔːl; -kɑːl/ noun
1.
[ U ] a system of fixed rules and formal behaviour used at official meetings, usually between governments :
a breach of protocol
the protocol of diplomatic visits
2.
[ C ] ( technical ) the first or original version of an agreement, especially a treaty between countries, etc.; an extra part added to an agreement or treaty :
the first Geneva Protocol
It is set out in a legally binding protocol which forms part of the treaty.
3.
[ C ] ( computing ) a set of rules that control the way data is sent between computers
4.
[ C ] ( technical ) a plan for performing a scientific experiment or medical treatment
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WORD ORIGIN
late Middle English (denoting the original minute of an agreement, forming the legal authority for future dealings relating to it): from Old French prothocole , via medieval Latin from Greek prōtokollon first page, flyleaf, from prōtos first + kolla glue. Sense 1 derives from French protocole , the collection of set forms of etiquette to be observed by the French head of state, and the name of the government department responsible for this (in the 19th cent.).