interveneverb/ˌɪntəˈviːn/

• 1

  To become involved in a situation, so as to alter or prevent an action.

  • The police had to be called to intervene in the fight.
  • Nature film-makers are discouraged from intervening in the events they are attempting to capture on film.
• 2

  To occur, fall, or come between, points of time, or events.

  • An instant intervened between the flash and the report.
  • […] it is plain, that shaking off a Power, which Force, and not Right, hath set over any one, though it hath the Name of Rebellion; yet is no Offence before God, but that which he allows and countenances, though even Promises and Covenants, when obtain’d by force, have intervened.
• 3

  To occur or act as an obstacle or delay.

  • Nothing intervened to prevent the undertaking.
  • The weather intervened before the contest could get under way.
• 4

  To say (something) in the middle of a conversation or discussion between other people, or to respond to a situation involving other people.

  • Young Scarfe stared, astounded. “You haven’t met before,” Mrs. Gould intervened. “Mr. Decoud—Mr. Scarfe.”
  • “That sounds suspiciously like bigotry to me,” intervened Maitland, sweetening his impertinence with a dimpled smile.
• 5

  To come between, or to be between, persons or things.

  • The Mediterranean intervenes between Europe and Africa.
  • 1668, Joseph Glanvill, Plus Ultra, or, The Progress and Advancement of Knowledge since the Days of Aristotle, London: James Collins, Chapter 11, p. 79, How defective the Art of Navigation was in elder Times, when they Sailed by the observation of the Stars, is easie to be imagin’d: For in dark weather, when their Pleiades, Helice, and Cynosura were hidden from them by the intervening Clouds, the Mariner was at a loss for his Guide, and exposed to the casual conduct of the Winds and Tides.
• 6

  lawIn a suit to which one has not been made a party, to put forward a defense of one's interest in the subject matter.

  • an application for leave (i.e. permission) to intervene