سِينٌ

One of the letters of the alphabet: (S, M, L, K:) [i. e., the name of that letter: (see article س:)] of the masculine gender as being supposed to be a حَرْف [or letter], and feminine as being supposed to be a كَلِمَة [or word]. (L.) The saying فُلَانٌ لَا يَحْسِنُ سِنَهُ means Such a one will not form well one of the three شُعَب [i. e. teeth, or cusps,] of his س. (S, L.)