noun
lying on one's belly; belly crawl
Refers to the position of lying flat on the stomach, or the action of crawling on the belly. Often used in contexts like military training, baby development, or exercise.
赤ちゃんが腹ばいで遊んでいる。
The baby is playing while lying on its belly.
訓練で腹ばいになって前に進んだ。
During training, I got down on my belly and crawled forward.
うつ伏せ also means lying face down, but is more general and commonly used in everyday situations. 腹ばい emphasizes the belly being in contact with the ground and often implies crawling or a specific prone position.
Compound of 腹 (はら, belly) and the continuative form of 這う (はう, to crawl), literally 'belly-crawling'.