From Longman Dictionary of Contemporary Englishan only childan only childCHILDa child who has no brothers or sisters → the one and only at one4(2), → (only) time will tell at time1(36) → only
Examples from the Corpus
an only child• And I was an only child.• E is for Ethel For most of my life I was an only child.• I was brought up by adoptive parents as an only child.• Shared nannies are becoming more popular and other children can provide stimulation and company if yours is an only child.• Sometimes I think I was intended to be an only child, and got born into a large family by a mistake.• The princess grew up thinking she was an only child but one day discovered she had twelve brothers.• Maman had given the impression she was an only child, she thought, but was that the truth?• It must be terrible to lose an only child; to lose any child. 