Where does “great-great-nephew” come from?

great-great-nephew (English) comes from English great-nephew, from English nephew, from Middle English nevew, from Old French neveu, from Latin nepōs, from Proto-Italic nepōts, from Proto-Indo-European népōts — grandson; descendant; nephew.

Ancestry of “great-great-nephew”, step by step

great-great-nephew traces back through two separate lines of ancestry.

via English great-nephew

StepLanguageWordMeaning
1Englishgreat-nephew
2EnglishnephewA son of one's sibling, brother-in-law, or...
3Middle EnglishnevewA nephew; A grandson or granddaughter; Any other...
4Old Frenchneveunephew; grandson
5Latinnepōs
6Proto-Italicnepōtsgrandson; nephew
7Proto-Indo-Europeannépōtsgrandson; descendant; nephew

via English Great

StepLanguageWordMeaning
1EnglishGreatTaking much space; large
2Middle Englishgretegreat; massive; amazing
3Old Englishgrēatgreat, large; big, thick, coarse, massive
4Proto-West Germanicgraut
5Proto-Germanicgrautazcoarse, crude; big, large
6Proto-Indo-Europeanǵʰer-to yearn for; to enclose; bowels, intestines
Every word from Proto-Indo-European népōts