'Half-sister' definitions:

Definition of 'half-sister'

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

Definition of 'Half-sister'

From: GCIDE
  • Half-sister \Half"-sis`ter\ (-s[i^]s`t[~e]r), n. A sister by one parent only. [1913 Webster]