The palm of the hand—the inner surface from the base of the fingers to the wrist, used for holding and sensing touch.
赤ちゃんの手のひらは柔らかくて温かい。
A baby's palm is soft and warm.
手のひらに汗をかいて緊張しているのがわかる。
You can tell he's nervous because his palms are sweaty.
掌に刻まれた線を見せてください。
Please show me the lines on your palm.