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.
Refers specifically to the eldest son, whereas 第二子 is gender-neutral and simply means second child.
Standard kanji spelling.
Variant using Arabic numeral 2 instead of 二.
Compound of 第 (ordinal prefix) + 二 (two) + 子 (child).