PIE base ‘to join’
Other derivatives include yoke through Germanic, join, jugular, adjust, jostle, junta, conjugal, subjugate, and juxtapose through Latin, and zygote and syzygy through Greek.
“The root *yeug– is continued by words in most of the branches of the Indo-European language family, which indicates that the speakers of Proto-Indo-European used draft animals to pull their ploughs and draw their wagons.” See note at *wegh-, PIE root of ‘wagon’ and ‘way’.
[Pokorny, i̯eu-2, i̯eu̯ə-, i̯eu̯-g-, ‘to tie together, yoke’, pp. 508–510]