Interstitial
Etymology
From Latin "interstitium" ("a space between"), from "inter-" (between) and "sistere" (to stand). Long used in anatomy and physics for tissue and gaps between cells or atoms, it now also names web ads that load between pages and, figuratively, the margins of experience.
adjective · /in-ter-STISH-ul/
Occupying the small spaces or gaps between things.
What it names
A precise word for the in-between — the leftover slivers of time, space, or structure that fall between the main parts.
Example
She wrote her novel in interstitial moments — subway rides, waiting rooms, the ten minutes before sleep.
Related idea
Liminal names a threshold you’re crossing, charged with transition; interstitial is flatter — simply the gap between, without the sense of passage.