IPA: /ˈprəʊtəkɒl/
KK: /ˈproʊtəkɔl/
A set of rules or guidelines that explain how something should be done, especially in formal situations.
The scientists followed the established protocol during the experiment.
A set of rules or guidelines that dictate how things should be done, especially in formal situations or technical processes.
The scientists followed the safety protocol to ensure a secure experiment.
Protocol is formed from "pro-" (meaning for or in favor of) and "tocoll" (from Greek "tókon", meaning to call or to announce). The word originally referred to a preliminary draft or a record of a call or announcement, particularly in diplomatic contexts.
Think of 'for' ('pro-') something being 'called' or 'announced' ('tocoll') — that's why protocol refers to the formal rules or records of communication.
No commonly confused words.