intercedent
Interceding: Passing between; mediating
Near-synonyms: intercessionary, intercessory
Where it comes from
Probably by way of French intercedent (adjective), which seems to be more commonly attested than this English adjective. Ultimately from Latin intercedens, present participle of intercedere, and possibly borrowed twice by English, with the later borrowing being a learned borrowing.
Adapted from the Wiktionary entry intercedent (CC BY-SA 4.0).