A person raised as the sole child in a household. (noun)
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Use "only child" in a sentence
"Ramsgate, 14 September, 1852; only child of Augustus Charles Pugin"
"In middle age Atticus had married a cousin, Caecilia Pilia, who bore him a girl, Caecilia Attica, his only child and heir to his fortune."
"Amazingly, a couple of years later Ridley left the Church of England and converted to Islam, quitting her journalist position at the Sunday Express, leaving her only child behind in Britain, and moving to Qatar.11"