The Case and Mood Endings

Iʿrāb (إعراب) is the hallmark of formal Arabic. It applies to nouns, adjectives, and present-tense verbs. While many words change their endings, some words are mabnī (مبني), meaning their final form is not changed by a syntactic case or mood governor; they may still conjugate or have different person forms, such as past-tense verbs, imperative verbs, personal pronouns, and most interrogative nouns. Note that demonstrative pronouns and relative pronouns are fixed except in their dual forms, which are declinable. Interrogatives are inherently fixed regardless of their position in the sentence, with the notable exception of ayyu, which is declinable. Present-tense verbs also become fixed on a sukūn when attached to the Nūn of Femininity or on a fatḥa when the Nūn of Emphasis attaches directly to the stem. Forms with intervening dual or plural subject markers need their own analysis.

1. Nouns and Adjectives (Cases):
Nouns change their endings based on three main 'cases'. Singular nouns and broken plurals use short vowels or Tanwīn, while duals and regular masculine plurals use letters. Crucially, Genitive (Jarr) is unique to nouns; verbs are never majrūr.

• The Nominative (Rafʿ): Ends in ḍamma (-u/-un). Used for the doer, as well as the subject and predicate. Duals use -āni and plurals use -ūna.
• The Accusative (Naṣb): Ends in fatḥa (-a/-an). Used for the direct object. Duals and plurals use -ayni and -īna. Note that regular feminine plurals take a kasra here.
• The Genitive (Jarr): Ends in kasra (-i/-in). Used after prepositions or as the second part of an iḍāfa (muḍāf ilayh). Note that diptotes take a fatḥa in the genitive unless they have the definite article or are in the muḍāf (first part of possession) position, in which case they take a kasra.

Special mention goes to The Five Nouns (like father and brother), which use long vowels (wāw, alif, yāʾ) to show case instead of short vowels.

2. Verbs (Moods):
Present-tense verbs change their endings depending on their role. Crucially, Jussive (Jazm) is unique to verbs; nouns are never majzūm.

• The Indicative: The default state, ending in ḍamma or retaining the nūn in the Five Verbs.
• The Subjunctive: Used after particles like أن or لن, resulting in a fatḥa or dropping the nūn.
• The Jussive: Triggered by particles like لم or the Lā of Prohibition, resulting in a sukūn, deletion of a final weak letter, or dropping the nūn.

3. Why it matters:
In daily dialects, these endings are mostly dropped. Formal grammar retains these distinctions, although ordinary writing often omits short-vowel marks and careful speech normally uses pause forms at pauses. Endings can help identify grammatical roles when word order changes; some endings are only understood, as with a final alif, so they do not remove every ambiguity.