intervention - noun

the act of intervening (as to mediate a dispute, etc.)

a policy of intervening in the affairs of other countries

the act or fact of interposing one thing between or among others

(law) a proceeding that permits a person to enter into a lawsuit already in progress; admission of person not an original party to the suit so that person can protect some right or interest that is allegedly affected by the proceedings

care provided to improve a situation (especially medical procedures or applications that are intended to relieve illness or injury)

intervention - thesaurus

intercession   interference   interposition   treatment