noun
second child
Refers to the second-born child in a family. Often used in formal or statistical contexts.
彼は第二子として生まれた。
He was born as the second child.
第二子の出産予定日は来月です。
The due date for the second child is next month.
Compound of 第 (ordinal prefix) + 二 (two) + 子 (child).