protocol

1. (now chiefly historical) The minutes, or official record, of a negotiation or transaction; especially a document drawn up officially which forms the legal basis for subsequent agreements based on it.Examples: "Another account says that, on the morning of the 31st of May, the king delivered to the prince-royal the crown, the sceptre, and the key of his treasure and gave him his blessing. The privy-counsillor Vockerodt drew up at his desire a protocol of the transaction."countablehistoricaluncountable

2. (international law, now rare) An official record of a diplomatic meeting or negotiation; later specifically, a draft document setting out agreements to be signed into force by a subsequent formal treaty.Examples: "The terms of this protocol formed the basis for the Treaty of London signed by the British, French and Russian governments on 6 July 1827."archaiccountableuncountable

3. (international law) An amendment to an official treaty.Examples: "The 1992 Protocol amended the definitions of other terms, including ‘ship’, ‘oil’ and ‘incident’: Art. 2."countableuncountable

4. (sciences) The original notes of observations made during an experiment.Examples: "The following is an abstract of the protocol of the experiment: Tumour extract.—A measured 16 c.c. of minced Rous Sarcoma tissue was ground with sand and extracted with 400 c.c. of 0.8-per-cent. saline."Synonyms: procedurecountableuncountable

5. (sciences) The precise method for carrying out or reproducing a given experiment.countableuncountable

6. (by extension) An accepted code of conduct; acceptable behaviour in a given situation or group.Examples: "For those uncertain in the protocol of handshaking a formula for the perfect handshake has been devised by scientists at the University of Manchester."; "TfW has staff enforcing mask protocols at all the busy stations and most travellers oblige, albeit some with ill grace."Synonyms: policybroadlycountableuncountable