Irab (الإعراب) is the Arabic grammatical case system. It determines the vowel ending a word takes based on its role in the sentence: is it the subject, the object, or is it following a preposition? In fully vowelled text, irab is visible. In unvowelled everyday writing, irab is invisible in most words but still affects spelling and grammar decisions in important ways.
The Three Cases
| Case | Arabic name | Marker | Main uses |
|---|---|---|---|
| Nominative | مرفوع | ـُ / ـٌ (damma) | Subject (فاعل), predicate of nominal sentence (خبر) |
| Accusative | منصوب | ـَ / ـً (fatha) | Direct object (مفعول به), adverbs, several other functions |
| Genitive | مجرور | ـِ / ـٍ (kasra) | After prepositions, second word of إضافة |
Case 1: Nominative (مرفوع)
The nominative case is used for the subject of a verb sentence, and for both the subject (مبتدأ) and predicate (خبر) in a nominal sentence.
| Sentence type | Example | Nominative word |
|---|---|---|
| Verbal sentence, subject | كتبَ الطالبُ الدرسَ | الطالبُ (damma) |
| Nominal sentence, subject | الطالبُ مجتهدٌ | الطالبُ (damma) |
| Nominal sentence, predicate | الطالبُ مجتهدٌ | مجتهدٌ (tanween damm) |
Case 2: Accusative (منصوب)
The accusative is the busiest case in Arabic. It applies to direct objects, many adverbial expressions, and several other functions.
| Function | Arabic term | Example |
|---|---|---|
| Direct object | مفعول به | قرأتُ الكتابَ |
| Adverb of manner | حال | جاء مسرعاً |
| Adverb of time/place | ظرف | جلستُ أمامَه |
| After إنَّ and sisters | اسم إن | إنَّ الطالبَ مجتهدٌ |
| Absolute object | مفعول مطلق | ضرب ضرباً شديداً |
Case 3: Genitive (مجرور)
The genitive case has two triggers: prepositions and the construct (إضافة). Every noun that follows a preposition is genitive, and the second noun in an إضافة is genitive.
| Trigger | Example | Genitive word |
|---|---|---|
| After preposition | ذهبتُ إلى المدرسةِ | المدرسةِ (kasra) |
| Second of إضافة | كتابُ الطالبِ | الطالبِ (kasra) |
| After بـ (attached) | كتبتُ بالقلمِ | القلمِ (kasra) |
Where Irab Affects Unvowelled Writing
Even when you do not write diacritics, irab affects spelling in these situations.
| Situation | Nominative | Oblique (acc/gen) |
|---|---|---|
| Sound masculine plural | المعلمون | المعلمين |
| Dual | الكتابان | الكتابين |
| Five nouns (الأسماء الخمسة) | أبوه | أباه / أبيه |
The Five Exceptional Nouns (الأسماء الخمسة)
Five common Arabic nouns show their case through a long vowel rather than a short vowel diacritic. These are: أب (father), أخ (brother), حم (father-in-law), فو (mouth), ذو (possessor of). They behave differently from all other nouns.
| Noun | Nominative | Accusative | Genitive |
|---|---|---|---|
| أب (father) | أبوه | أباه | أبيه |
| أخ (brother) | أخوه | أخاه | أخيه |
| ذو (possessor) | ذو علم | ذا علم | ذي علم |
Frequently Asked Questions
Do I need to know irab to write correct Arabic?
You need to understand the principles of irab even if you do not write full tashkil. Decisions like whether to write ـون or ـين on a plural, or whether a dual ends in ـان or ـين, all depend on knowing the grammatical role of the word in its sentence.
What is the difference between مرفوع and منصوب?
مرفوع is the case of subjects and predicates, marked by damma. منصوب is the case of direct objects and adverbial expressions, marked by fatha. When fully vowelled text is read, these distinctions are audible as ـُ versus ـَ.