12th cent. From Latin dare 'id.'
From Proto-Italic *dide- 'id.' From Proto-Indo-European *di̯-deh3- "to be giving." Reduplication of *deh3- "to give" to form the imperfective aspect.
Western Vulgar Latin: Asturian dar, Portuguese dar, Galician dar, Catalan dar, Italian dare; Eastern Vulgar Latin: Aromanian dau, dari Romanian da, dare, Sardinian dare
Oscan didet "will give," Umbrian teřa "gives," Paelignian datas "given," Venetic doto "gave," Vestian didet "gives," Pre-Samnite tetet "gave," Marsian ded "given"
Celtic: Old Irish do-rata "giveable;" Balto-Slavic: Old Church Slavonic dati, Lithuanian dúoti; Albanian: (archaic) dhae; Hellenic: Ancient Greek δίδωμι (dídomi); Armenian: tam; Indo-Iranian: Sanskrit dádāti, Young Avestan daδāiti; Anatolian: Hittite dā-i "to wed," Cuneiform Luwian lā-
For the origin of irregular form doy
"I am," see -oy
The root *deh3- meant both give and take at once, and the root probably ment "to stretch out one's hand" in Pre-Proto-Indo-European. As one linguist wrote on this root: "The root *dō- means “give” in all Indo-European languages. However, there is one language which fails to conform to this definition: in Hittite, dā- means “take” and pai- ‘give’... The notion of “give” and “take” are thus linked in prehistoric Indo-European." ~ E. Benveniste, Indo-European Language and Society (1973)