tanween

Tanween, or nunation, is a feature of Arabic orthography consisting of three diacritic marks placed at the end of an indefinite noun to indicate indefiniteness and, in traditional grammar, the noun’s case ending. The three forms are tanween al-damm (dammatan), tanween al-fath (fathatan), and tanween al-kasr (kasratan). They correspond to the grammatical endings -un, -an, and -in: dammatan marks nominative, fathatan marks accusative, and kasratan marks genitive.

In use, tanween appears only on indefinite nouns and signals their case in Classical and Modern Standard Arabic. For example, the indefinite noun kitab (a book) can take: kitabun (a book, nominative), kitabān (a book, accusative), kitabīn (a book, genitive). The written marks are the diacritics along with the noun, and definite nouns do not take tanween.

Historically, tanween reflects the historical presence of the letter nūn (nunation) at the end of words in certain constructions. In contemporary writing, tanween is common in formal registers, religious texts, and language learning materials, but diacritics are often omitted in everyday Arabic writing and many daily speech varieties do not pronounce the final n in casual speech. In careful reading or recitation, the tanween and its underlying -n ending may be pronounced, whereas in general discourse it is typically not spoken.