Where does “Keynesianist” come from?

Keynesianist (English) comes from English ist, from English -ist, from Old French -iste, from Latin -ista, from Ancient Greek -ιστής, from Ancient Greek -τής, from Proto-Hellenic -tās.

Ancestry of “Keynesianist”, step by step

Keynesianist traces back through two separate lines of ancestry.

via English ist

StepLanguageWordMeaning
1EnglishistA practitioner or supporter of an ism
2English-istAdded to words to form nouns denoting
3Old French-iste
4Latin-ista-ist; one who practises or believes
5Ancient Greek-ιστήςAlternative form of -τής; -ist
6Ancient Greek-τήςAppended to verbs to form agent nouns
7Proto-Hellenic-tās

via English Keynesian

StepLanguageWordMeaning
1EnglishKeynesianOf or pertaining to an economic theory based on...
2English-ianFrom, related to, or like; One from, belonging...
3EnglishHobbesianInvolving unrestrained, selfish, and uncivilized...
4EnglishHobbesa surname
5EnglishRobert
6Anglo-NormanRobert
Every word from Proto-Hellenic -tāsEvery word from English -istEvery word from Ancient Greek -τής