middleborn adjective 1noun 1forms 1 adjective1 •Born as the middle child to a parent or family.On the positive side, middleborn children are good negotiators and adaptable; they often feel little need to "control." — 1996 noun1 •The middle child to be born to a parent or family.A middleborn who feels left out may become unsure about his place in the family. — 1986 formsmiddleborns