The story
- German · borrowed fromGrenz“border”
- English todaygrenz ray
From German Grenz (“border”) (since the effects were thought to be on the border between ultraviolet light and traditional X-rays) + ray.
Etymology from Wiktionary, CC BY-SA 4.0.
grenz ray
Today it means: An ultrasoft X-ray used in treating various skin diseases. Full definition →
German Grenz