趾

Left-side foot radical — pictograph of a leg ending in a foot (口 ankle on top, 止 toes below). The indexing radical, naturally so: 趾 is the toe specifically. Foot-radical family covers movement and lower-body anatomy: 跑 to run, 跳 to jump, 跟 heel, 踝 ankle, 踏 to step on.

Right side 止 supplies the sound: zhǐ → zhǐ, identical pinyin and tone. 止 is itself an ancient pictograph of a footprint (the same shape at the bottom of 足), originally meaning 'foot' before shifting to 'stop / halt.' Double semantic echo: a foot-character built from foot + foot, with the right side also locking the sound.