From Proto-Tai *rɯːwꟲ (“to know”). Cognate with Thai รู้ (rúu), Northern Thai ᩁᩪ᩶, Isan ฮู้, Lao ຮູ້ (hū), Lü ᦣᦴᧉ (huu²), Shan ႁူႉ (hṵ̂u), Ahom 𑜍𑜥 (rū) or 𑜍𑜤𑜈𑜫 (ruw), Zhuang rox, Saek รอ.
ꪭꪴ꫁ ('hụ)