thirdborn adjective 2noun 1forms 1 adjective2 •Born as the third child to parent or family.Mary, the thirdborn Bennett child in the novel Pride and Prejudice, receives the least attention. •Third of a particular type to be born to a parent or family.Prince Arthur was Queen Victoria's thirdborn son and her seventh child overall. noun1 •The third child born to a parent or family. formsthirdborns
