'Stepbrother' definitions:

Definition of 'stepbrother'

(from WordNet)
noun
A brother who has only one parent in common with you [syn: stepbrother, half-brother, half brother]

Definition of 'Stepbrother'

From: GCIDE
  • Stepbrother \Step"broth`er\, n. A brother by the marriage of one's father with the mother of another, or of one's mother with the father of another. [1913 Webster]