plural protocols
1 : a system of rules that explain the correct conduct and procedures to be followed in formal situations
[noncount]
The soldier's actions constitute a breach of military protocol.
[count]
They did not follow the proper diplomatic protocols.
What is the proper protocol for declining a job offer?
2 [count] : a plan for a scientific experiment or for medical treatment
an experimental protocol
a simplified treatment protocol
3 [count] formal : a document that describes the details of a treaty or formal agreement between countries
the Geneva Protocol of 1925
4 [count] computers : a set of rules used in programming computers so that they can communicate with each other
an Internet protocol