noun
hill behind a house or village
Refers to the mountain or hill directly behind a settlement, often part of the local landscape.
家の裏山に小さな神社がある。
There is a small shrine on the hill behind my house.
noun
shady side of a mountain
The side of a mountain that receives little direct sunlight; often cooler and damper.
The shady side of the mountain gets no sun, so moss grows thickly there.
na-adjective
Internet slang pun on うらやましい (envious); used humorously to express jealousy.
See also: うらやましい
あの人の新車、裏山すぎる！
I'm so jelly of that person's new car!