Where does “ジーパン” come from?

ジーパン (Japanese) comes from Japanese パンツ, from English pants, from English pantaloons, from English pantaloon, from French pantalon, from Italian Pantalone, from Ancient Greek Παντελεήμων, from Ancient Greek ἐλεήμων — Creates transitive imperfective verbs from roots.

Ancestry of “ジーパン”, step by step

ジーパン traces back through two separate lines of ancestry.

via Japanese パンツ

StepLanguageWordMeaning
1Japaneseパンツpants, underpants; pants, trousers
2EnglishpantsAn outer garment that covers the body from the...
3EnglishpantaloonsAn article of clothing covering each leg...
4EnglishpantaloonAn aging buffoon; Trousers reminiscent of the...
5Frenchpantalontrousers UK, pants US
6ItalianPantalonePantaloon (Venetian theatrical character)
7Ancient GreekΠαντελεήμων
8Ancient Greekἐλεήμωνpitiful, merciful
9Ancient GreekἐλεέωI have pity on, take pity on, show mercy to
10Ancient Greek-έωUsed to form verbs from nouns, adjectives and...
11Proto-Indo-European-éyetiForms causative imperfective verbs from roots;...
12Proto-Indo-European-yetiCreates transitive imperfective verbs from roots

via Japanese ジーンズ

StepLanguageWordMeaning
1Japaneseジーンズjeans
2EnglishJeansplural of Jean
3Englishjean fustian
4Middle Englishfustianstrong cotton fabric
5Old FrenchfustaineA cotton fabric ancestral to modern fustian
6Medieval Latinfustaneum
7Latinfustisa knobbed stick, a cudgel, staff, club
8Proto-Indo-Europeangʷʰen-to strike, slay, kill
9Proto-Indo-Europeanbʰon-
Every word from Proto-Indo-European -yetiEvery word from Ancient Greek -έωEvery word from Proto-Indo-European -éyeti