What is the exact meaning (or interpretation) of Yaseen? (as the initial verse of Surah-Yasin)

As you are aware, Surah Yasin consists of 88 verses and it begins with Ya, Seem (Yaseen) Yasin: > بِسْمِ اللَّـهِ الرَّحْمَـٰنِ الرَّحِيمِ > > يس (1) والقرآن الحکیم (2) إِنَّكَ لَمِنَ الْمُرْسَلِين (3) علی صراط > مستقیم (4) تنزیل العزیز الرحیم > > > > > Ya, Seen. (1) By the wise Qur'an. (2) Indeed you, [O Muhammad], are > from among the messengers, (3) On a straight path. (4) [This is] a > revelation of the Exalted in Might, the Merciful, (5) …… > > > ( tanzil.net / 36:1 ) As you see, the initial verse of this Surah is "Yaseen". Its meaning in many translations is written Yaseen too. But I couldn’t find any specific meaning for it (according to an authentic translation). I'd be thankful if anyone says that **what is the exact meaning or interpretation of this verse? (I mean "Yaseen")** *(Note: I'm looking for authentic sources, please)*