膝坊主

(1)the upper side of the thighs of a seated person; "he picked up the little girl and plopped her down in his lap"

(2)着席した人の腿の上部

(3)hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella

(4)脛骨と腓骨を大腿骨に結びつけ、膝蓋によって前部を保護されている人間の脚にある蝶番関節