injunctive

early 15c., from Late Latin iniunctionem (nominative iniunctio) "a command," noun of action from past participle stem of Latin iniungere "impose, inflict, bring upon," literally "attach to," from in- "on" (from PIE root *en "in") + iungere "to join together," from nasalized form of PIE root *yeug- "to join."

word-forming element making adjectives from verbs, meaning "pertaining to, tending to; doing, serving to do," in some cases from Old French -if, but usually directly from Latin adjectival suffix -ivus (source also of Italian and Spanish -ivo). In some words borrowed from French at an early date it has been reduced to -y (as in hasty, tardy).