An intermediate cause or agency, a mediator. Obsolete.

An intermediate agency, instrument, or channel; a means; esp. a means or channel of communication or expression. Frequently in by (also through) the…

An intermediate agent, intermediary, medium; esp. in earlier Chemistry and Physics, a substance serving as a means of some natural action or process…

Something that serves as a means of some action between other things; a medium: = intermedium, n. 3. Obsolete.

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