noun
A flat stone placed in a garden path or shallow water for walking on.
庭の踏み石を伝って歩く。
Walk along the stepping stones in the garden.
飛び石 are stepping stones placed with gaps, often in a Japanese garden, while 踏み石 is a more general term for a stepping stone.
Compound of 踏み (fumi, 'stepping') + 石 (ishi, 'stone').