city of Thuringia, Germany, site of a famous university that dates to 16c.; attested from 9c. as Jani, from Old High German jani "strip of mown grass," ultimately from PIE root *ei- "to go."
jellybean
jellyfish
jellyroll
Jemima
Jemmy
Jena
jennet
Jennifer
Jenny
jeopardise
jeopardize