The indeclinable noun: definition, rule and eight classes

1. The first sense of an indeclinable noun

الْبَابُ الثَّانِي: فِي الِاسْمِ الْمَبْنِيِّ. وَهُوَ اسْمٌ وَقَعَ غَيْرَ مُرَكَّبٍ مَعَ غَيْرِهِ.
Translation: The second chapter concerns the indeclinable noun. The first case described is a word not yet joined with another in a grammatical construction.

The opening describes a word cited in isolation: it has not yet become a subject, object, or predicate in a grammatical sentence.

2. Examples of isolated words

مِثْلَ: أ، ب، ت، ث، وَمِثْلَ: وَاحِد، وَاثْنَان، وَثَلَاثَة، وَكَلَفْظِ «زَيْد» وَحْدَهُ.
Translation: Examples include isolated letter names, the words “one, two, three,” and the word “Zayd” when uttered alone.

Do not conclude that wāḥid or Zayd is inherently indeclinable in ordinary syntax. The examples concern citation in isolation.

3. Actually fixed, potentially declinable

فَإِنَّهُ مَبْنِيٌّ بِالْفِعْلِ عَلَى السُّكُونِ وَمُعْرَبٌ بِالْقُوَّةِ.
Translation: Such a word is actually fixed on sukūn when cited alone, but potentially declinable: within syntax it can receive grammatical case.

Bi-l-fiʿl refers to its present citation form; bi-l-quwwa to its grammatical potential. This is not permanent inherent indeclinability.

4. Put Zayd into sentences

In isolation, زَيْدْ can end in sukūn when stopping.

جَاءَ زَيْدٌ. — Zayd came: subject (fāʿil), nominative, ḍamma.
رَأَيْتُ زَيْدًا. — I saw Zayd: object, accusative, fatḥa.
مَرَرْتُ بِزَيْدٍ. — I passed by Zayd: genitive, kasra.

The changing endings demonstrate that the noun itself is declinable.

5. Parsing Zayd in all three cases

جَاءَ زَيْدٌ: jāʾa is past tense; Zayd is fāʿil, nominative by ḍamma.

رَأَيْتُ زَيْدًا: raʾaytu is past tense with -tu as its subject; Zayd is a direct object, accusative by fatḥa.

مَرَرْتُ بِزَيْدٍ: marartu is verb and subject; bi- is a preposition; Zayd is genitive by kasra.

A pause-ending does not remove a noun’s capacity for iʿrāb.

6. Resemblance to inherently fixed forms

أَوْ شَابَهَ مَبْنِيَّ الْأَصْلِ بِأَنْ يَكُونَ فِي الدَّلَالَةِ عَلَى مَعْنَاهُ مُحْتَاجًا إِلَى قَرِينَةٍ كَالْإِشَارَةِ.
Translation: Or the noun resembles an inherently indeclinable form, for instance when identifying its intended referent needs a contextual cue such as pointing.

Unlike the isolated-word case, this concerns an inherently fixed form even in sentences. Contextual reference is one way the source explains the resemblance.

7. The book’s demonstrative example

نَحْوُ: «هَؤُلَاءِ» وَنَحْوِهَا.
Translation: For example, «هَؤُلَاءِ» (“these people”) and comparable demonstratives.

The meaning of hāʾulāʾi depends on demonstrative context. Its built form stays the same when used as subject, object, or after a preposition.

8. One form, three syntactic positions

جَاءَ هَؤُلَاءِ. — These people came.
Hāʾulāʾi: demonstrative, built on kasra, in nominative position as subject.

رَأَيْتُ هَؤُلَاءِ. — I saw these people.
Hāʾulāʾi: in accusative position as object.

مَرَرْتُ بِهَؤُلَاءِ. — I passed by these people.
After bi-, it is in genitive position.

Its ending remains unchanged in all three.

9. Inflection versus grammatical position

When Zayd is the subject, a visible ḍamma marks the nominative: marfūʿ bi-l-ḍamma.

When hāʾulāʾi is the subject, its ending stays fixed: mabnī ʿalā l-kasr fī maḥalli rafʿ.

Similarly, fī maḥalli naṣb and fī maḥalli jarr name its syntactic position without changing the noun’s built ending.

10. Few letters and particle-like meaning

أَوْ يَكُونَ عَلَى أَقَلَّ مِنْ ثَلَاثَةِ أَحْرُفٍ، أَوْ تَضَمَّنَ مَعْنَى الْحَرْفِ.
Translation: Or its form has fewer than three letters, or it incorporates a meaning associated with a particle.

The text names further resemblances to particles. It does not mean every two-letter noun must be indeclinable; for example يَدٌ is declinable.

11. A crucial two-letter counterexample

هَذِهِ يَدٌ. — This is a hand: yadu(n) is a nominative predicate.
رَأَيْتُ يَدًا. — I saw a hand: yada(n) is an accusative object.
أَمْسَكْتُ بِيَدٍ. — I held a hand: yadi(n) is genitive after bi-.

Thus letter count alone is not a reliable universal test. The book speaks of specific patterns of resemblance.

12. Dhā and compound numerals

The book cites ذَا and compound numerals from 11 to 19.

هَذَا طَالِبٌ. — This is a student: hādhā is a demonstrative built on sukūn, in nominative position as subject.

جَاءَ أَحَدَ عَشَرَ طَالِبًا. — Eleven students came: aḥada ʿashara is built on fatḥa in both parts and acts as subject; ṭāliban is an accusative specification (tamyīz).

Teaching qualification: the first part of اثنا عشر follows dual declension, so it should not be forced into the same pattern.

13. Inherent indeclinability persists

وَهَذَا الْقِسْمُ لَا يَصِيرُ مُعْرَبًا أَصْلًا.
Translation: This second class—the inherently indeclinable form—does not become declinable.

This applies to the inherently indeclinable class, not the isolated “Zayd” mentioned earlier, which becomes declinable in a sentence.

14. The governing rule for mabnī

وَحُكْمُهُ: أَنْ لَا يَخْتَلِفَ آخِرُهُ بِاخْتِلَافِ الْعَوَامِلِ.
Translation: The rule is that its final form does not change as the governing syntactic factor changes.

A governor (ʿāmil) may change syntactic function, but it does not change the inherent final form of a mabnī noun.

15. Names for fixed ending vowels

وَحَرَكَاتُهُ تُسَمَّى ضَمًّا وَفَتْحًا وَكَسْرًا، وَسُكُونُهُ وَقْفًا.
Translation: Its fixed final movements are called ḍamm, fatḥ, and kasr; its fixed sukūn is termed waqf in the book.

These terms describe a built ending, not necessarily nominative, accusative, or genitive case. This is the distinction emphasized by the text.

16. Same vowel, different function

In hāʾulāʾi, the final kasra is its built ending even when it is a subject.

In Zaydin, the kasra is a genitive case marker caused by a preposition or iḍāfa.

The vowel looks alike; the grammatical explanation is different.

17. The source lists eight classes

وَهُوَ عَلَى ثَمَانِيَةِ أَنْوَاعٍ: الْمُضْمَرَاتُ، وَأَسْمَاءُ الْإِشَارَاتِ، وَالْمَوْصُولَاتُ، وَأَسْمَاءُ الْأَفْعَالِ، وَالْأَصْوَاتُ، وَالْمُرَكَّبَاتُ، وَالْكِنَايَاتُ، وَبَعْضُ الظُّرُوفِ.
Translation: The book lists eight classes: pronouns, demonstratives, relative nouns, verb-names, sound-words, compounds, indefinite/indirect expressions (kināyāt), and certain adverbs.

All eight categories are displayed. Their fuller rules belong to later lessons; here we establish identification and basic examples.

18. 1 — Pronouns

أَنَا، أَنْتَ، هُوَ، نَحْنُ are pronouns, referring to speaker, addressee, or someone absent.

هُوَ مُجْتَهِدٌ. — He is diligent.
Huwa: detached pronoun built on fatḥa, in nominative position as mubtadaʾ. Mujtahidun: nominative predicate.

Its fixed fatḥa does not make it accusative.

19. 2 — Demonstratives

هَذَا، هَذِهِ، هَؤُلَاءِ point to persons or things.

هَذَا كِتَابٌ. — This is a book.
Hādhā: demonstrative built on sukūn, in nominative position as subject; kitābun: nominative predicate.

Qualification: certain dual demonstratives (e.g., hādhāni) are declined; not every demonstrative follows one unqualified pattern.

20. 3 — Relative nouns

الَّذِي، الَّتِي are relative nouns identified by a following relative clause (ṣila).

جَاءَ الَّذِي نَجَحَ. — The one who succeeded came.
Alladhī: relative noun built on sukūn, in nominative position as fāʿil; najaḥa: past verb whose subject is an implied huwa. The relative clause has no independent iʿrāb position.

The relative noun’s built form remains fixed.

21. 4 — Verb-names

صَهْ is an imperative verb-name (ism fiʿl), meaning “Be quiet!”

صَهْ! — Be quiet!
Ṣah: a verb-name of command built on sukūn, with an implied subject “you.”

It conveys an imperative meaning but belongs grammatically to the class of verb-names.

22. 5 — Sound-words

The book separately counts aṣwāt, conventional sound-names, as a category.

Teaching example: غَاقِ represents a crow’s call.

Detailed usage comes later. For now, distinguish the book’s category of sound-names from verb-names.

23. 6 — Compounds

Some compound nouns function as one grammatical unit even though written in two parts.

حَضَرَ أَحَدَ عَشَرَ رَجُلًا. — Eleven men attended.
Aḥada ʿashara: compound numeral built on fatḥa in both parts, in nominative position as subject; rajulan: accusative tamyīz.

A word can be built yet occupy a nominative position.

24. 7 — Kināyāt

Kināyāt include indirect words for persons, things, or quantities.

Teaching example: كَمْ كِتَابًا قَرَأْتَ؟ — How many books did you read?
Kam: interrogative noun built on sukūn, in accusative position as fronted object; kitāban: accusative specification; qaraʾta: past verb with -ta as subject.

The book here names the category; full treatment follows elsewhere.

25. 8 — Certain adverbs

The book says only certain adverbs are built; not all adverbial nouns.

Teaching example: جَلَسْتُ حَيْثُ جَلَسَ الْمُعَلِّمُ. — I sat where the teacher sat.
Ḥaythu: locative adverb built on ḍamm, in accusative position; the clause j alasa al-muʿallimu is its genitive complement.

The final ḍamma is built, not a nominative case marker.

26. All eight classes at a glance

1. Pronouns — هُوَ
2. Demonstratives — هَذَا
3. Relatives — الَّذِي
4. Verb-names — صَهْ
5. Sound-names — غَاقِ
6. Certain compounds — أَحَدَ عَشَرَ
7. Kināyāt — كَمْ
8. Certain adverbs — حَيْثُ

These are recognition examples, not an assertion that each category has no declinable exceptions.

27. Three errors to avoid

1. Wrong: not every kasra marks genitive case; in hāʾulāʾi it is part of the built form.
2. Wrong: isolated Zayd with pause is not inherently built; in sentences it has Zaydun/Zaydan/Zaydin.
3. Wrong: not every short noun is built; yadun is declinable.

Correct method: identify the word class, its syntactic role, and why its final vowel appears.

28. Reading the syntactic position

جَاءَ هَؤُلَاءِ. — Hāʾulāʾi is built on kasra, in nominative position as fāʿil.
رَأَيْتُ هَؤُلَاءِ. — Built on kasra, in accusative position as object.
مَرَرْتُ بِهَؤُلَاءِ. — Built on kasra, in genitive position.

Summary: one fixed form can occupy three different case positions.

29. Pause versus inherent building

A word cited in isolation can be stopped upon: Zaydْ illustrates this.

In جَاءَ زَيْدٌ, it is fully declinable.

By contrast, هَؤُلَاءِ keeps its built ending across grammatical positions.

Keep the book’s actually fixed / potentially declinable distinct from inherently indeclinable.

30. Consolidating the rule

A muʿrab noun can change its ending with the governing context: Zaydun / Zaydan / Zaydin.

An inherently mabnī noun keeps its built form across contexts: hāʾulāʾi.

Case position (maḥall) is its syntactic role even when the ending does not vary.

Recall all eight categories; the book next begins a detailed treatment of pronouns.