stepbrother

noun

Etymology: Etymology tree Proto-Indo-European *(s)tew- Proto-Germanic *steupa- Proto-West Germanic *steupa- Old English stēop- Middle English step- English step- Proto-Indo-European *bʰréh₂tēr Proto-Germanic *brōþēr Proto-West Germanic *brōþer Old English brōþor Middle English brother English brother English stepbrother From step- + brother.

1. The son of one's stepparent by a previous relationship.
2. The stepson of one's parent who is not one's half-brother.