An Etymological Dictionary of the German Language/Annotated/sechs

by Friedrich Kluge

sechs, numeral, ‘six,’ from Middle High German and Old High German sëhs; a common Teutonic and primitively Aryan numeral; compare Old Saxon sehs, Dutch zes, Anglo-Saxon and English six, Old Icelandic sehs, Gothic saíhs; primitively Aryan seks (and sweks). Compare Sanscrit šaš, Zend χšvaš, Greek ἕξ, Latin sex, Welsh chwech, Old Slovenian šestĭ.