From ụnrụn (“hair”) + *umu (“groin, genitalia”), umu is likely an obsolete word referring to the groin or genitalia, and may be euphemistic. Compare with Igbo amụ̀. The "uru" is a result of vowel harmony in Ekiti, where the nasal "u," is unnasalized in certain compounds, see this in urùgbọ̀n (“beard”) and urúmọlẹ̀.