WordDictionary

Verb:

• legal In a suit to which one has not been made a party, to put forward a defense of one's interest in the subject matter.
• To come between, or to be between, persons or things; -- followed by between; as, the Mediterranean intervenes between Europe and Africa.
• To interpose; as, to intervene to settle a quarrel; get involved, so as to alter or hinder an action
• To occur, fall, or come between, points of time, or events; as, an instant intervened between the flash and the report; nothing intervened ( i. e., between the intention and the execution) to prevent the undertaking.