1A baby or very young infant — an affectionate everyday term, commonly used in conversation.
赤ちゃんが夜中に泣いて、あまり眠れなかった。
The baby cried in the middle of the night, so I couldn't sleep well.
赤ちゃん用のミルクとおむつを買いに行く。
I'm going to buy formula and diapers for the baby.
公園で赤ちゃんを連れた親子をよく見かける。
I often see parents with babies at the park.
妹に赤ちゃんが生まれたので、来週会いに行く予定だ。
My younger sister had a baby, so I'm planning to visit them next week.