Tanween (التنوين) is the double vowel mark placed at the end of Arabic nouns and adjectives to indicate indefiniteness and grammatical case at the same time. It is one of the most useful and most misused features of written Arabic. Getting it right requires understanding both what it marks and, just as importantly, where it cannot appear.
What Is Tanween?
Tanween adds a final /n/ sound to a noun. It is written as a doubled vowel mark and it serves two purposes at once: it signals that the noun is indefinite (like "a" in English), and it marks the grammatical case of that noun in the sentence.
The Three Types
| Name | Mark | Sound | Case | Example |
|---|---|---|---|---|
| Tanween Damm (تنوين ضم) | ـٌ | -un | Nominative (subject) | كتابٌ |
| Tanween Fath (تنوين فتح) | ـً | -an | Accusative (object, adverb) | كتاباً |
| Tanween Kasr (تنوين كسر) | ـٍ | -in | Genitive (after preposition, in إضافة) | كتابٍ |
Tanween Fath and the Extra Alef
When tanween fath (ـً) is added to most nouns, an extra alef (ا) is written to support it. This alef is silent, it just carries the double fatha in writing.
| Noun | With tanween fath | Note |
|---|---|---|
| كتاب | كتاباً | Alef added |
| بيت | بيتاً | Alef added |
| مدرسة | مدرسةً | No alef , ends in taa marbuta |
| سماء | سماءً | No alef , ends in hamza on alef |
When Tanween Is Forbidden
This is where most mistakes happen. Tanween cannot appear in the following situations.
| Situation | ❌ Wrong | ✅ Correct |
|---|---|---|
| Definite noun (with ال) | الكتابٌ | الكتابُ |
| Proper nouns (most) | محمدٌ (as object) | محمداً |
| First word of إضافة | كتابُ الطالبٌ | كتابُ الطالبِ |
| Diptotes (ممنوع من الصرف) | مساجدٌ | مساجدُ |
| Pronouns | هوٌ | هو |
Diptotes: The Tanween Exception
Diptotes (الممنوع من الصرف) are nouns and adjectives that refuse both tanween and kasra case ending. They take fatha in both the accusative and genitive, and damma in the nominative. Only when they are definite (with ال) do they behave normally and take full case endings.
| Type | Examples | Indefinite genitive |
|---|---|---|
| Broken plural on فَعَالِل/أَفَاعِل pattern | مساجد، أحمد، أفضل | مساجدَ (not مساجدٍ) |
| Feminine proper nouns | فاطمة، مريم، زينب | فاطمةَ (not فاطمةٍ) |
| Colours and defects (أفعل pattern) | أحمر، أكبر، أصغر | أحمرَ (not أحمرٍ) |
Tanween in Adverbial Expressions
Tanween fath appears on many frozen adverbial expressions even when the noun is semantically definite. These are fixed forms that you learn as vocabulary items rather than apply rules to.
- أحياناً (sometimes), طبعاً (of course), جداً (very) , all use tanween fath
- أولاً، ثانياً، ثالثاً , ordinal adverbs always take tanween fath
- شكراً، عفواً، صباحاً، مساءً , greeting and time expressions use tanween fath
Common Mistakes
| ❌ Wrong | ✅ Correct | Mistake |
|---|---|---|
| الطالبُ مجتهدٌ | الطالبُ مجتهدٌ ✓ (this is correct) | Note: predicate adjective takes tanween when indefinite |
| ذهبتُ إلى مدرسةٍ الكبيرة | ذهبتُ إلى المدرسةِ الكبيرةِ | Tanween on definite noun |
| رأيتُ مساجدٍ كثيرة | رأيتُ مساجدَ كثيرة | Tanween on diptote |
| كتابُ طالبٍ الذكي | كتابُ الطالبِ الذكيِّ | Missing ال making noun definite in إضافة |
Frequently Asked Questions
Can a definite noun take tanween?
No. Tanween marks indefiniteness. A noun with ال never takes tanween. This is one of the most reliable rules in Arabic grammar.
Why does tanween fath add an alef?
The alef is a support letter to carry the double fatha in writing. It is not pronounced independently. Nouns ending in taa marbuta or hamza on alef do not add this extra alef.
What is the difference between tanween and the letter ن?
Tanween is a written mark (doubled vowel diacritic) that produces a /n/ sound at the end of a noun. The letter ن is a full consonant that is always written. Tanween only appears when the text is fully vowelled, though its written mark (ـً ـٍ ـٌ) can appear without full tashkil.