Thuluth (Persian: ثلث‎‎ sols, Turkish: Sülüs, from Arabic: ثلث‎ ṯuluṯ "one-third") is a script variety of Islamic calligraphy invented by the Persian Ibn Muqlah Shirazi, which made its first appearance in the 11th century CE (fourth Hijri). The straight angular forms of Kufic were replaced in the new script by curved and oblique lines. In Thuluth, one-third of each letter slopes, from which the name (meaning "a third" in Arabic) comes.