Formally the dual of a stem *(H)oḱto-(“four fingers”). This erstwhile singular seems to appear in Avestan𐬀𐬱𐬙𐬌- (ašti-, “breadth of four fingers”) and appears to have been borrowed into Proto-Kartvelian as *otxo-(“four”).
^ Fortson, Benjamin W. (2004, 2010) Indo-European Language and Culture: An Introduction, Oxford: Blackwell
^ Adams, Douglas Q. (2013), “okt”, in A Dictionary of Tocharian B: Revised and Greatly Enlarged (Leiden Studies in Indo-European; 10), Amsterdam, New York: Rodopi, →ISBN, pages 115-116
^ Adams, Douglas Q. (2013), “oktante”, in A Dictionary of Tocharian B: Revised and Greatly Enlarged (Leiden Studies in Indo-European; 10), Amsterdam, New York: Rodopi, →ISBN, page 116
Bjørn, Rasmus (2019), “Nouns and Foreign Numerals: Anatolian ‘Four’ and the Development of the PIE Decimal System”, in Matilde Serangeli and Thomas Olander, editors, Dispersals and Diversification: Linguistic and Archaeological Perspectives on the Early Stages of Indo-European (Brill's Studies in Indo-European Languages & Linguistics; 19), Leiden and Boston: Brill, →DOI, pages 57, 62–64
