Medical term for symptoms caused by reduced oxygen at high altitudes.
富士山に登ったとき、高所病になって頭が痛くなった。
When I climbed Mt. Fuji, I got altitude sickness and had a headache.
Compound of 高所 (high place) and 病 (illness). The exact derivation is uncertain, but the term directly describes sickness from being at a high altitude.