A broken plural changes the internal shape of the singular instead of merely attaching ـون/ـين or ـات. Compare كتاب kitāb → كتب kutub “book → books” and رجل rajul → رجال rijāl “man → men.” Consonants may be regrouped around different vowels, long vowels may appear or disappear, and a prefix may be added.
Broken plurals follow recurring templates, but there is no universal rule that predicts the right template for every noun. The practical skill is to recognize common patterns while learning each frequent noun as a singular–plural pair.
What “broken” means
The root consonants normally remain identifiable, but the stem's internal prosodic pattern changes.
| Singular | Broken plural | Change | Meaning |
|---|---|---|---|
| كِتَاب kitāb | كُتُب kutub | long vowel removed; internal vowels changed | book(s) |
| قَلَم qalam | أَقْلَام ʾaqlām | أ prefix plus long ā | pen(s) |
| بَيْت bayt | بُيُوت buyūt | new internal syllable and long ū | house(s) |
| رَجُل rajul | رِجَال rijāl | vowel pattern changed; long ā added | man/men |
| مَدِينَة madīna | مُدُن mudun | stem shortened; ة removed | city/cities |
كتاب، كتابان، كتب.
kitāb, kitābān, kutub.
A book, two books, books.
بيت، بيتان، بيوت.
bayt, baytān, buyūt.
A house, two houses, houses.
The dual remains productive even when the plural is broken. You form بيتان from the singular stem because it means exactly two; بيوت is the lexical plural for the plural category.
Why prediction is limited
Patterns make an unfamiliar plural look plausible after you encounter it. They do not guarantee which plural a particular singular selects. Similar-looking singulars can choose different patterns, and one noun can have more than one established plural with differences in frequency, meaning, or register.
For example, مكتب maktab “office” has مكاتب makātib, but كتاب kitāb “book” has كتب kutub. Guessing مكاتب as the plural of كتاب produces the real word “offices,” not a creative version of “books.”
هذا كتاب، وهذه مكاتب.
hādhā kitāb, wa-hādhihi makātib.
This is a book, and these are offices.
Some nouns also permit both a sound plural and a broken plural, often with usage preferences. Those preferences are lexical and can develop historically; they should be checked rather than derived from a loose semantic rule.
Gender and agreement are separate from plural shape
The internal pattern does not by itself determine agreement. Human/rational broken plurals normally take plural gender agreement; nonhuman/non-rational broken plurals normally take feminine singular agreement.
وصل رجال جدد.
waṣala rijālun judud.
New men arrived.
رجال is human masculine plural, so adjective جدد is masculine plural. Because the verb comes first, وصل remains singular masculine.
الرجال الجدد وصلوا.
ar-rijālu l-jududu waṣalū.
The new men arrived.
With the subject first, the verb becomes plural وصلوا.
وصلت الكتب الجديدة.
waṣalati l-kutubu l-jadīda.
The new books arrived.
كتب is a morphologically masculine broken plural, but it is nonhuman. Verb وصلت and adjective الجديدة are therefore feminine singular.
البيوت القديمة جميلة.
al-buyūtu l-qadīmatu jamīla.
The old houses are beautiful.
This feminine singular agreement is not a property of one plural template. It applies across sound and broken nonhuman plurals. Rational, individuated, or personified beings may license rational agreement according to intended reference, but ordinary things and animals as a class follow the nonhuman pattern.
Case and tanwīn: two major behaviors
Many broken plurals are triptotes. They take ordinary nominative -un, accusative -an, and genitive -in when indefinite, and lose tanwīn when definite.
هذه كتب مفيدة.
hādhihi kutubun mufīda.
These are useful books. (Nominative -un connected.)
اشتريت كتبا مفيدة.
ʾishtaraytu kutuban mufīda.
I bought useful books. (Accusative -an connected.)
بحثت عن كتب مفيدة.
baḥathtu ʿan kutubin mufīda.
I looked for useful books. (Genitive -in connected.)
A major group of broken plurals—especially patterns such as مفاعل mafāʿil and مفاعيل mafāʿīl—are diptotes. When indefinite, they take no tanwīn and use -a for both accusative and genitive. With الـ, or when used as the construct head of an iḍāfa and annexed to a following noun, normal genitive -i returns.
زرت مساجد قديمة.
zurtu masājida qadīma.
I visited old mosques. (Indefinite diptote accusative -a.)
صليت في مساجد قديمة.
ṣallaytu fī masājida qadīma.
I prayed in old mosques. (Indefinite diptote genitive -a.)
صليت في المساجد القديمة.
ṣallaytu fī l-masājidi l-qadīma.
I prayed in the old mosques. (Definite genitive -i.)
Thus “broken plural” is a stem class, not a single declension. You must also know whether that plural is triptote or diptote.
Citation form and inflected form
A dictionary may list a bare or pausal plural such as كتب kutub or مساجد masājid. In connected full speech, syntax supplies an ending: كتبٌ/كتبًا/كتبٍ or مساجدُ/مساجدَ. Ordinary unvocalized spelling hides most of these contrasts.
الطلاب قرؤوا الكتب في المكتبة.
aṭ-ṭullābu qaraʾū l-kutuba fī l-maktaba.
The students read the books in the library.
The visible plural الكتب does not show its accusative -a in ordinary spelling; the fully vocalized reading does.
Contemporary informational use
أظهرت التقارير أن أسعار البيوت ارتفعت هذا العام.
ʾaẓharati t-taqārīru ʾanna ʾasʿāra l-buyūti rtafaʿat hādhā l-ʿām.
The reports showed that house prices rose this year.
Both التقارير “reports” and أسعار “prices” are nonhuman broken plurals. Their verbs أظهرت and ارتفعت are feminine singular. This remains true even though the two nouns follow different broken-plural templates.
For a structured inventory of frequent shapes, continue to Common Broken-Plural Patterns.
Common Mistakes
Adding a sound suffix to a lexical broken plural
❌ كتابون
Incorrect — the ordinary plural of كتاب is كتب.
✅ كتب.
kutub.
Books.
Guessing the wrong real word as a plural
❌ مكاتب كثيرة للقراءة
Incorrect for the intended meaning ‘many books to read’ — مكاتب means offices.
✅ كتب كثيرة للقراءة.
kutubun kathīratun lil-qirāʾa.
Many books to read.
Combining “two” with a plural noun
❌ اثنان كتب
Incorrect for neutral ‘two books’ — use the dual noun.
✅ كتابان.
kitābān.
Two books.
Giving a nonhuman broken plural plural agreement
❌ الكتب الجديدون وصلوا
Incorrect — nonhuman كتب takes feminine singular agreement.
✅ الكتب الجديدة وصلت.
al-kutubu l-jadīdatu waṣalat.
The new books arrived.
Treating every broken plural as an ordinary triptote
❌ صليت في مساجد
Incorrect full reading if مساجد is given genitive -in; this indefinite diptote uses -a without tanwīn.
✅ صليت في مساجد.
ṣallaytu fī masājida.
I prayed in mosques. (Diptote genitive ending demonstrated.)
Key Takeaways
- Broken plurals alter the singular stem internally; learn each frequent singular and plural together.
- Templates aid recognition but do not provide a universal prediction rule.
- Most broken plurals are triptotes, while major patterns such as مفاعل and مفاعيل are diptotes.
- Human/rational reference takes plural agreement; nonhuman/non-rational reference normally takes feminine singular agreement.
Now practice Arabic
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Start learning Arabic →Related Topics
- Sound Feminine Plural ـاتA2 — Form the ـات plural, use its nominative and accusative-genitive cases, and distinguish human from nonhuman agreement.
- Common Broken-Plural PatternsA2 — Recognize five high-frequency broken-plural templates and connect each shape to its lexical, case, and agreement behavior.
- Masculine and Feminine NounsA1 — Understand Arabic's two grammatical genders and how gender controls agreement across singular, human-plural, and nonhuman-plural phrases.