noun / adjective
intermediary
in-ter-MEE-dee-air-ee/ˌɪntərˈmiːdieri/
Something that connects two otherwise separate stages or parties.
The intermediary passes the buyer's payment to the seller.

Etymology
The pieces describe a position in the middle, between other things. That spatial idea became a social role: an intermediary acts between other parties as a mediator.
In context
… the intermediary in a conflict shuttles backwards and forwards repeatedly between the parties
More examples
- We communicate with the owner through an intermediary.
- The nonprofit acts as an intermediary between donors and schools.
- The material passes through an intermediary stage before becoming a finished product.
Forms
intermediary · intermediaries
Similar words
- mediator
- Helps parties resolve disagreements, not merely exchange information.
- broker
- Usually arranges business deals rather than linking process stages.
- intermediate
- Describes a middle stage without necessarily connecting separate parties.