'Half-brother' definitions:

Definition of 'half-brother'

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

Definition of 'Half-brother'

From: GCIDE
  • Half-brother \Half"-broth`er\ (-br[u^]th`[~e]r), n. A brother by one parent, but not by both. [1913 Webster]