From Longman Dictionary of Contemporary Englishfirstbornfirst‧born /ˈfɜːstbɔːn $ ˈfɜːrstbɔːrn/ noun [singular] CHILDyour first child —firstborn adjective her firstborn son
Examples from the Corpus
firstborn• Often, the firstborn are favoured from the moment of birth.• They were expecting a son, brother to 2-year-old Hannah, their firstborn. 