enjoin (v.)

c. 1200, engoinen, "to prescribe, impose" (penance, etc.), from stem of Old French enjoindre (12c.) "impose (on), inflict; subject to; assign (to)," from Latin iniungere "to join, fasten, attach;" figuratively "to inflict, to attack, impose," from in- "on" (from PIE root *en "in") + iungere "to join together" (from nasalized form of PIE root *yeug- "to join"). Related: Enjoined; enjoining.