Tanween (التنوين), also known as nunation, is the addition of an extra "n" sound to the end of a noun, represented in writing by doubled diacritical marks. There are three types: tanween fat-ha (ـً), tanween damma (ـٌ), and tanween kasra (ـٍ). Tanween is one of the primary markers of an indefinite noun in Arabic.
Each type of tanween corresponds to a grammatical case. Tanween damma (ـٌ) indicates the nominative case (مرفوع), tanween fat-ha (ـً) indicates the accusative case (منصوب), and tanween kasra (ـٍ) indicates the genitive case (مجرور). For example: كتابٌ (a book, nominative), كتابًا (a book, accusative), كتابٍ (a book, genitive).
Tanween disappears in several situations: when the definite article ال is added (الكتابُ instead of كتابٌ), when the noun is in an إضافة construction (كتابُ الطالبِ instead of كتابٌ), and when certain suffixes are added. Understanding when tanween appears and disappears is essential for correct Arabic writing and pronunciation.
In Tajweed (Quranic recitation), tanween has specific pronunciation rules depending on the letter that follows it. These include إظهار (clear pronunciation), إدغام (merging), إقلاب (conversion), and إخفاء (hiding). The Tajweed course on Ilm Al Lughah covers these rules in detail, connecting them to the grammatical foundation you learn in Nahw.