Where does “great toenail” come from?

great toenail (English) comes from English toenail, from English toe, from Middle English to, from Middle English tone, from Latin tonus, from Ancient Greek τόνος, from Proto-Hellenic tónos, from Proto-Indo-European tónos — to stretch, to extend.

Ancestry of “great toenail”, step by step

great toenail traces back through two separate lines of ancestry.

via English toenail

StepLanguageWordMeaning
1EnglishtoenailThe thin, horny, transparent plate covering the...
2EnglishtoeEach of the five digits on the end of the foot;...
3Middle Englishtotoe; to; too
4Middle Englishtonethe one
5LatintonusThe stretching or straining of a rope; A strain;...
6Ancient Greekτόνοςrope, cord; chord; tone, note
7Proto-Hellenictónosrope, cord; tension
8Proto-Indo-Europeantónossomething stretched; chord, fiber, string
9Proto-Indo-Europeanten-to stretch, to extend

via English great toe

StepLanguageWordMeaning
1Englishgreat toebig toe
2Middle Englishgret toThe big toe largest toe of the foot
3Middle EnglishgretAlternative form of grete; great
Every word from Proto-Indo-European ten-Every word from Proto-Indo-European tónosEvery word from Proto-Hellenic tónos