1. one's stepfather's son or stepmother's son by a previous marriage.
Examples from the web for stepbrother
- Sometimes on the weekends, my older stepbrother and stepsister live with us, too.
- The stepfather, stepmother, stepbrother or stepsister.
British Dictionary definitions for stepbrother
noun 1. a son of one's stepmother or stepfather by a union with someone other than one's father or mother respectively
Word Origin and History for stepbrother