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: 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: Inherited from Proto-Italic *wīkəntī, from Proto-Indo-European *h₁wi-(h₁)-ḱm̥t-ih₁, from *dwi-(h₁)-dḱm̥t-ih₁, *dwi(h₁)dḱm̥ti (“two tens, two decades”). See also vīcēsimus and vīciēs. Cognate with Sanskrit विंशति (viṃśatí), Ancient Greek εἴκοσι (eíkosi), Old Irish fiche, Welsh ugain, Breton ugent, Tocharian A wiki.