counterside
/kaʊntəˌsaɪd/Definitions
1. noun
The side opposite to the main or visible side of something, especially a landscape or a mountain.
“The counterside of the mountain range was more treacherous to climb than the front.”
2. noun
A side opposite to the main or visible side of a particular thing, especially a coin or a medal.
“The counterside of the coin bore the image of a historic figure.”