ست

سَاتٌّ ذ [ Sixth ]. You say, جَاآءَ فُلَانٌ سَادِسًا and سَادِيًا and سَاتًّا [ Such a one came sixth ]; سادسا being formed from سِدْسٌ; and ساتّا, from سِتَّةٌ and سِتٌّ: in ساديا, the [latter] س [of سادسا] is changed into ى; for certain letters in other cases are sometimes so changed; as in أَمَّا and أَيْمَا and تَسَنَّنَ and تَسَنَّى, and تَقَضَّضَ and تَقَضَّى, and تَلَعَّعَ and تَلَعَّى, and تَسَرَّرَ and تَسَرَّى. (ISk, S.)