CPA, Syr. ܚܐ܂ ܚܐܬܐ‏; pl. ˀaḥwān, ˀaḥwāṯā even in those dialects that lose the initial syllable in the singular; JLAtg abs. and var. for "my sister" : אְַחָת (and 1 time for absolute!); CPA emph./suff. usually without initial aleph.

For PAT2776 see PAT 335.
As with the masculine form, whether familial relationship is always the case in the earlier texts is not clear; nor, of course, is the difference between actual sister and kinswoman always clear to us.