腿
もも · momo · JLPT N1 · noun
femur
腿 — flesh radical 月 (肉) + 退 tuì (phonetic)
腿 is a semantic-phonetic compound. The left side 月 is the 'flesh/body' radical, marking it as a body part. The right side 退 supplies the sound (tuì → tuǐ). It's a relatively late character; older Chinese used 股 and 腳 for leg-related meanings.