foster sister foster sire • foster son · · · Info · Definitions · Synonyms · Characters · · foster sister · · Text Common · · Latin · · Scripts 13 · · Length 4 · · Syllables Definitions · · · (noun) your foster sister is a female who is not a daughter of your parents but who is raised by your parents. Synonyms: foster-sister, foster sister. · · Noun Definition 1 Synonyms · · · foster-sister · · Synonym 1 Characters · · space U+0020 e latin small letter e U+0065 f latin small letter f U+0066 i latin small letter i U+0069 o latin small letter o U+006F r latin small letter r U+0072 s latin small letter s U+0073 t latin small letter t U+0074