interim

Interim is an indeclinable adverb built from inter, "between", and it means what it looks like: in the space between two other things. Prose uses it to park one strand of a narrative while another runs, which is why historians reach for it every few paragraphs. Interea does the same job and the two are near enough interchangeable.

Later Latin adds a second sense that classical writers do not have: "for the moment, provisionally", something true until a proper arrangement replaces it. That is the sense English borrowed whole, in an interim report and in ad interim, the phrase still used for an official holding a post temporarily. Do not confuse it with interea loci or with the preposition inter, which needs an accusative after it.