مُثَنًّى
1.
[pass. particle n. of 2.
2.
Dualized: a dual.
3.
مُثَنَّاةٌ فَوْقِيَّةٌ
Marked with two points above: an epithet added to تاء to prevent its being mistaken for باء or ثاء or ياء. And مُثَنَّاةٌ تَحْتِيَّةٌ
Marked with two points below: an epithet added to ياء to prevent its being mistaken for باء or تاء or ثاء.]
4.
الطَّويلُ المُثَنَّى (assumed tropical:) That which passes away [out of sight, or disappears,] by length; mostly used of a thing that is long without breadth. (TA.)