köken: From Middle High German zweinzec, from Old High German zweinzug, from Proto-Germanic *twaintigaz, *twai tigiwiz. Cognate with Dutch twintig, West Frisian tweintich, English twenty, Danish tyve. The form zwanzig goes back to dialects that had early on lowered Middle High German -ei- to [aɪ̯] (especially Bavarian); elsewhere the contraction yielded zwenzig, which waned around 1700 along with the…
köken: Inherited from Middle French vingt, from Old French vint, from Latin vīgintī, from Proto-Indo-European *h₁wih₁ḱm̥ti, *dwi(h₁)dḱm̥ti. The Latin -g- was regularly lost in Old French, but was added back to the spelling in Middle French (now placed after the -n- in order to maintain the pronunciation).
köken: From Proto-Turkic *yẹgirmi (“twenty”). Cognate with Old Turkic 𐰘𐰏𐰼𐰢𐰃 (y²gr²mi), Azerbaijani iyirmi, Bashkir, Tatar егерме (yegerme), Kyrgyz жыйырма (jıyırma), Turkish yirmi, Uyghur يىگىرمە (yigirme), Uzbek yigirma, etc.
köken: Inherited from Volga Bulgar جيرم (ciyermi), from Proto-Turkic *yẹgirmi. Cognate with Khalaj yigirmi, Turkish yirmi, Uzbek yigirma, Bashkir егерме (yegerme), and Yakut сүүрбэ (süürbe).
köken: From Old Galician-Portuguese vinte, vynte, viinte, from Latin vīgintī, from Proto-Indo-European *h₁wih₁ḱm̥ti, from *dwi(h₁)dḱm̥ti(h₁) (“two tens, two decades”), *dwi(h₁)dḱm̥ti.
aile: vintão, vinte e cinco, vinte e dois, vinte e nove, vinte e oito, vinte e quatro, vinte e seis, vinte e sete, vinte e três, vinte e um
köken: Believed to be cognate with 果(は)て (hate, “end”), with 20 signifying the "limit" of one person's counting ability using two feet and two hands. Already in declining use by the Heian period in favour of 二十(にじゅう) (nijū). Note also Ainu ホッ (hot, “twenty”).
köken: First attested as Late Old Korean 戌沒 in the Jīlín lèishì (鷄林類事 / 계림유사), 1103. In the hangul script, first attested in the Worin seokbo (月印釋譜 / 월인석보), 1459, as Middle Korean 스믏 (Yale: sumulh).