Where does “Flachpfirsich” come from?

Flachpfirsich (German) comes from German Pfirsich, from Latin persica, from Latin Persicus, from Ancient Greek περσικός, from Ancient Greek Πέρσης, from Old Persian 𐎱𐎠𐎼𐎿, from Proto-Iranian párcuš, from Proto-Indo-Iranian párćuš — chest; rib.

Ancestry of “Flachpfirsich”, step by step

Flachpfirsich traces back through two separate lines of ancestry.

via German Pfirsich

StepLanguageWordMeaning
1GermanPfirsichpeach
2Latinpersicawalnut; nominative plural of persicum; accusative...
3LatinPersicusPersian
4Ancient GreekπερσικόςPersian from Persia; pertaining to the Persians
5Ancient GreekΠέρσηςa Persian
6Old Persian𐎱𐎠𐎼𐎿a Persian
7Proto-Iranianpárcušrib
8Proto-Indo-Iranianpárćušrib
9Proto-Indo-Europeanpérḱuschest; rib

via German Flach

StepLanguageWordMeaning
1GermanFlachshallow wide and not deep
2Middle High Germanvlach
3Old High Germanflahflat, smooth
4Proto-West Germanic*flak
5Proto-Germanicflakazflat
6Proto-Indo-Europeanpl̥kehflat surface
Every word from Proto-Indo-European pérḱus