From Longman Dictionary of Contemporary Englishstepsonstep‧son /ˈstepsʌn/ noun [countable] SSFFAMILYa son that your husband or wife has from a relationship before your marriage
Examples from the Corpus
stepson• What I would impose on a stepson for is some Internet lessons.• Justin, a cameraman, and his stepson, Tom.• I've tried to love my stepson but I really resent him.• Robert, my stepson, is not to be given his grandfather's inheritance until he is thirty.• My husband sometimes scolds my stepson but more often blames my son.• I told you - Barbara's stepson.• The stepson was one of nine young men who killed themselves on the reservation that year.• A: No disrespect to your stepson, but I would leave well enough alone. 