IPA: /ˈaʊtərmoʊst/
KK: /ˈaʊtərˌmoʊst/
The farthest away from the center or inside; the most external part.
The outermost layer of the Earth is called the crust.
Outermost → It is formed from "outer" (from Old English "ūtera", meaning external or outside) and "-most" (meaning the furthest or extreme). The word "outermost" means the furthest out or the most external part.
Think of something that is the "furthest outside" — "outer" means outside, and "-most" indicates the extreme position.