outermost layer
noun phraseUK /ˈaʊtəməʊst ˈleɪə/
US /ˈaʊtərˌmoʊst ˈleɪər/
The outermost layer is the very outside part that covers everything else.
The skin is the outermost layer of your body.
OTHER MEANINGS
2. The top layer of the ground or soil.
The outermost layer of soil dries out first in the sun.
3. The outside coat of paint or material on an object.
The outermost layer of paint protects the wood from rain.
4. The part of something that faces the outside world.
The outermost layer of the atmosphere helps block harmful rays.