noun
octuplet
Only when written 八つ子
Refers to eight siblings born from the same pregnancy. A rare but straightforward term.
彼女は八つ子を出産したというニュースを見た。
I saw the news that she gave birth to octuplets.
noun
eight-year-old child
Used to refer to a child who is eight years old. The kanji 八歳児 is rare; 八つ子 is more common for this meaning.
うちの八つ子はもうすぐ三年生になる。
Our eight-year-old will soon be a third grader.
Compound of 八つ (yatsu, 'eight') + 子 (ko, 'child'). The reading やつご is a regular rendaku form.