English protocol is an interesting word. From Greek, via Latin protocollum, πρωτοκολλον (prōtokollon) 'table of contents, first page/sheet κολλημα (kollēma) of a papyrus roll'. Cf. index and colophon.

I looked it up in the online OED and found that protocol can be used as a verb, meaning to "draw up protocols." I didn't know that.

They also had this interesting note:

"The history of the sense-development of this word belongs to mediæval Latin and the Romanic languages, esp. French; in the latter it has received very considerable extensions of meaning: see Du Cange, Cotgr., Littré, Hatz.-Darm., etc. The word does not appear to have at any time formed part of the English legal vocabulary; in Sc. from 16thc. probably under French influence; otherwise used only in reference to foreign countries and their institutions, and as a recognized term of international diplomacy in sense 2, until its comparatively recent entry into the general vocabulary of English in senses 5b, c."

We're familiar with 'protocol' meaning the complicated niceties of affairs of state, or similar codes of conduct for private affairs.

It surprised me to find that (although the word 'protocol' dates back to 1541) those familiar meanings are quite new. According to OED, they did not appear until the late 1940s and early 1950s.