ثُنَايءِىٌّ
1.
[a rel. n. from اِثْنَانِ, anomalously formed, but analogous with other rel. ns. from ns. of number, as رُبَاعِىٌّ ثُلَاثِىٌّ, &c., Of, or relating to, two things].
2.
كَلِمَةٌ ثُنَايءِيَّةٌ
A word comprising, or composed of, two letters; as يَدٌ, and دُمْ [or دَمٌ?]. (TA.)