Agency or action as an intermediary; the state or fact of serving as an intermediate agent, a means of action, or a medium of transmission…

= intervention, n. 2.

Intervention, mediation, agency.

figurative. The mediation, alteration, or distortion of something, usually something pure or absolute, arising from the medium of expression…

Intervention.

= intervention, n. 2b.

Intermediate agency; the fact of coming in or being employed as an intermediary. Of things.

The state of being intermediate; intermediateness; intermediate agency, intervention.

With mixture of sense 1: An intervening medium serving to transmit energy through space.

Something acting between persons or things, a medium, means. Also abstract: action as a medium, mediation, agency (of something).

gen. Intervening agency, instrumentality.