Where does “reptilism” come from?

reptilism (English) comes from English reptile, from Middle English reptil, from Old French reptile, from Late Latin reptile, from Latin reptilis, from Latin rēpō, from Proto-Italic rēpō, from Proto-Indo-European h₁reh₁p- — to creep.

Ancestry of “reptilism”, step by step

reptilism traces back through two separate lines of ancestry.

via English reptile

StepLanguageWordMeaning
1EnglishreptileA cold-blooded vertebrate of the class...
2Middle Englishreptil
3Old Frenchreptile
4Late Latinreptileneuter nominative singular of rēptilis; neuter...
5Latinreptiliscreeping, crawling
6Latinrēpōto creep, crawl
7Proto-Italicrēpō
8Proto-Indo-Europeanh₁reh₁p-to creep

via English ism

StepLanguageWordMeaning
1EnglishismAn ideology, system of thought, or practice that...
2English-ismUsed to form nouns of action or process or result...
3Latin-ismus-ism
4Ancient Greek-ισμόςForms abstract nouns
5Ancient Greek-μόςForms abstract nouns
6Proto-Indo-European-mósCreates action/result nouns from verb stems
Every word from Proto-Indo-European h₁reh₁p-Every word from Proto-Italic rēpōEvery word from Latin rēpō