toplayer
nounUK /ˈtɒpˌleɪə/
US /ˈtɑːpˌleɪər/
The top layer is the part on the very top of something.
The cake has a sweet top layer of chocolate.
OTHER MEANINGS
2. The highest level or rank in a group or system.
She reached the top layer of the company after years of hard work.
3. The upper stratum of soil or rock.
The top layer of soil was dry, but deeper down it was moist.
4. In computing, the highest level of a layered system or protocol.
The top layer of the software handles what the user sees.