"of a grammatical mode expressing command," 1825, with -ive + Latin iuss-, past participle stem of iubere "to bid, command, to order," from PIE root *ioudh- "to cause to move" (cognates: Sanskrit yudhya- "to fight," yodha- "to rebel;" Greek hysmine "battle, fight;" Lithuanian judėti "to move" (intransitive), judus "belligerent"). The sense evolution in Latin was from "cause to move" to "order." As a noun from 1836.
