an only child—a child without any brothers or sisters:
- I was an only child and he was an only child. For those basic reasons, I’ve always felt a connection to him.
the only child—
1. = only child, an:
- He was missing all the attention that was coming his way when he was the only child.
2. a single child involved in a situation:
- I remember Sumitro because he was the only child with parents from India.