1.
only child
A child who has no siblings.
私は一人っ子です。
I'm an only child.
一人っ子だから兄弟がほしかった。
Since I'm an only child, I wanted siblings.
最近は一人っ子の家庭が増えている。
Families with only children are increasing recently.
一人っ子 refers to a child with no siblings. The っ子 suffix gives a colloquial, familiar tone.
COMMON PATTERNS:
- 一人っ子で育つ: to grow up as an only child
- 一人っ子政策: one-child policy (China)
SOCIAL CONTEXT:
With Japan's declining birth rate (少子化), 一人っ子 families have become increasingly common. There is a common stereotype that only children are spoiled (甘やかされている) or selfish, though this is often inaccurate.
VARIANT:
一人子 is a more formal/literary alternative.