J / jūrāmentum
noun

jūrāmentum

gen. jūrāmenti · gender neuter · decl. 2nd
an oath; to take an oath, to swear
an oath (post-class. for jusjurandum), Dig. 22, 3, 25: praestare, to take an oath, to swear, Cod. 2, 56, 4.