ルイ
Ainu「砥石」
ruymedium
Both references explicitly attest the whetstone noun. The common ruy meaning intense or strong is a separate sense and supplies no evidence for 砥.
References
Occurrences (1)
- National Institute for Japanese Language and Linguistics · 乾巻 · Page 100, line 8 · ルイ
…〳〵食物を入る鉢マツンキ膳イタ盃台タカザラ皮惣名カブト革ルシ砥石ルイ素物イモカ椛皮の柄杓タツカツクミ笠カシヤ金コンカネ銀シロカネ銅フーレカネ鉄クフカ錫ヤイカネ ヤヽ…