The position of lying on one's back with the face or front side facing upward.
赤ちゃんを仰向きに寝かせて、様子を見てください。
Lay the baby on its back (facing upward) and keep an eye on them.
彼は仰向きに倒れて天井をじっと見ていた。
He fell on his back and stared up at the ceiling.
ヨガのクラスでは、まず仰向きでリラックスするポーズから始めます。
In the yoga class we start with a relaxing pose lying on our backs.