Dictionary.net

get involved, usually so as to hinder or halt an action; "Why did the U.S. not intervene earlier in WW II?"

get involved, so as to alter or hinder an action, or through force or threat of force; "Why did the U.S. not intervene earlier in WW II?"

be placed or located between other things or extend between spaces and events; "This interludes intervenes between the two movements"; "Eight days intervened"

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.

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

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.

A coming between; intervention; meeting.

To come between, or to be between, persons or things; - followed by between; as, the Mediterranean intervenes between Europe and Africa.

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.

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

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.

A coming between; intervention; meeting.

To come between, or to be between, persons or things; - followed by between; as, the Mediterranean intervenes between Europe and Africa.

To come or be situated; interfere.

To come between; interpose.