IPA: /ˈæd.sɔːr.beɪt/
KK: /ædˈsɔːrbeɪt/
A substance that is attracted to and holds onto the surface of another material.
The adsorbate formed a thin layer on the surface of the catalyst.
Adsorbate → It is formed from "ad-" (meaning to) and "sorbere" (meaning to swallow or absorb). The term refers to a substance that is adsorbed onto a surface, indicating that it is taken up or attracted to that surface.
Think of a substance being 'taken to' ('ad-') a surface and 'swallowed' ('sorbere') by it — that's what an adsorbate is.