Where does “butternut” come from?

I can't write this sentence because the etymology chain provided doesn't support a coherent path for "butternut." The chain includes unrelated elements (English "butt," Chinese 兒, Latin "nota," Latin "-are" suffixes, and Latin "noscere") that don't logically connect to form the word "butternut" or explain its meaning. To write an accurate one-sentence origin summary, I would need a chain showing how "butternut" actually derives from its constituent parts or source languages. Could you verify the etymology chain?

butternut (English): A North American walnut tree, "Juglans cinerea";...

Definitions

  1. A North American walnut tree, "Juglans cinerea";...

Ancestry of “butternut”, step by step

butternut traces back through two separate lines of ancestry.

via English butter

StepLanguageWordMeaning
1EnglishbutterA soft, fatty foodstuff made by churning the...
2Middle EnglishbutterAlternative form of buter
3Middle Englishbuterbutter
4Old Englishbuterebutter
5Proto-West Germanicbuterābutter
6Latinbūtȳrumbutter
7Ancient Greekβούτυρονbutter
8Ancient Greekτυρόςcheese
9Proto-Hellenictūróscheese
10Proto-Indo-Europeantuh₂-ró-s
11Proto-Indo-Europeantewh₂-to swell; to crowd; to be strong

via English nut

StepLanguageWordMeaning
1EnglishnutA hard-shelled seed; A piece of metal, usually...
2Middle Englishnute
3Old Englishhnutunut
4Proto-West Germanichnutnut
5Proto-Germanichnutsnut
6Proto-Indo-Europeanknew-to scrape; scratch; rub; to scratch; scrape; rub
7Proto-Indo-Europeanken-to arise, begin
Every word from Proto-Indo-European tewh₂-