Source : Webster's Revised Unabridged Dictionary (1913)

Intervene \In`ter*vene"\, v. i. [imp. & p. p. {Intervened}; p.
   pr. & vb. n. {Intervening}.] [L. intervenire, interventum, to
   intervene, to hinder; inter between + venire to come; akin to
   E. come: cf. F. intervenir. See {Come}.]
   1. To come between, or to be between, persons or things; --
      followed by between; as, the Mediterranean intervenes
      between Europe and Africa.

   2. 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.

   3. To interpose; as, to intervene to settle a quarrel.

   4. 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.
      --Abbott.

Source : WordNet®

intervening
     adj 1: occurring or falling between events or points in time; "so
            much had happened during the intervening years"
     2: standing between or separating two objects or areas;
        "Paris--where the same city lies on both sides of an
        intervening river"; "after reaching the top of the hill he
        looked across an intervening meadow to another line of
        hills"