From Aramaic ܬܪܬܝܢ (tartēn), from Proto-Semitic *ṯinatāni. Compare Harsusi ثَرت f (ṯart, “two”).
ܬ݂ܰܪܬ̤ (ṯarč) f (masculine ܐܶܬ݂ܶܪ (ʾeṯər))