noun
stone for cutting pubic hair (Edo-period public baths)
Archaic term for a stone used in Edo-period public baths to trim pubic hair. Only encountered in historical contexts.
江戸時代の銭湯には、毛切り石と呼ばれる石が置いてあったという。
It is said that in Edo-period public baths, there was a stone called a 'hair-cutting stone'.
Compound of 毛 (ke, 'hair'), 切り (kiri, 'cutting'), and 石 (ishi, 'stone'). The exact historical origin is uncertain, but the term straightforwardly describes its function.