In short

The previous lesson gave you plurals you build by adding something to the end of the word: ـونَ / ـينَ for men, ـاتٌ for women and for many feminine things. Those are the tidy ones, and they are the minority. Most Arabic nouns make their plural a different way entirely: they keep their consonants and rebuild everything else. كِتابٌ becomes كُتُبٌ. بَيْتٌ becomes بُيوتٌ. مَدْرَسَةٌ becomes مَدارِسُ. Nothing was appended - the word was poured into a new mould. Arabic grammar calls this جَمْعُ التَّكْسير, “the plural of breaking”, because the singular is broken up and reassembled. English keeps three or four fossils of the same idea (foot/feet, mouse/mice); in Arabic it is the normal way to make a plural.

There is one piece of bad news and one piece of good news. The bad: you cannot work out which mould a noun uses. قَلْبٌ and كَلْبٌ have exactly the same shape, and their plurals are قُلوبٌ and كِلابٌ. The mould is part of the word, like gender, and it has to be learned with the word. The good: a small number of moulds cover most of what you will read. Nine of them are tabled below, and after a few weeks you will recognise a broken plural on sight even in a word you have never met. The lesson ends with a related trick - collective nouns like شَجَرٌ and سَمَكٌ, where the plain word is the mass and the ending ة cuts one unit out of it.

The rule

1. Two plural systems; the broken one is the bigger. A sound plural (lesson 9) leaves the singular untouched and adds an ending: مُهَنْدِسٌ ← مُهَنْدِسونَ، مُعَلِّمَةٌ ← مُعَلِّماتٌ. A broken plural changes the vowels inside the word, and often adds a consonant at the front (أ or م) or a long vowel in the middle. Compare:

• sound: طَبيبَةٌ ← طَبيباتٌ (nothing inside the word moved)
• broken: طَبيبٌ ← أَطِبّاءُ (every vowel is different, and a new أ appeared)

Which system a noun uses is a fact about that noun. Sound masculine plurals are mostly limited to male human beings and participles; ـاتٌ is common but far from automatic. Everything else - including the great majority of everyday concrete nouns - breaks.

2. The mould belongs to the word, not to a rule. This is the point to accept early, because fighting it wastes months. Two nouns of identical shape routinely take different moulds:

• قَلْبٌ ← قُلوبٌ but كَلْبٌ ← كِلابٌ
• بَيْتٌ ← بُيوتٌ but شَيْخٌ ← شُيوخٌ and عَيْنٌ ← عُيونٌ (here they happen to agree)
• وَلَدٌ ← أَوْلادٌ but جَبَلٌ ← جِبالٌ

So treat the plural as a second half of the dictionary entry. When you write a new noun in your notebook, write two words: قَلَمٌ - أَقْلامٌ. Never one.

3. The nine moulds worth knowing first. They are set out in full in the next section. In prose, what each one is typically for:

• أَفْعال - the workhorse for short three-consonant nouns: قَلَمٌ ← أَقْلامٌ، وَلَدٌ ← أَوْلادٌ، بابٌ ← أَبْوابٌ، يَوْمٌ ← أَيّامٌ.
• فُعول - equally common, especially from nouns shaped فَعْل or فِعْل: بَيْتٌ ← بُيوتٌ، قَلْبٌ ← قُلوبٌ، دَرْسٌ ← دُروسٌ، عِلْمٌ ← عُلومٌ.
• فِعال - people and things alike: رَجُلٌ ← رِجالٌ، جَبَلٌ ← جِبالٌ، بَحْرٌ ← بِحارٌ. It also serves as the plural of the adjective فَعيل: كَبيرٌ ← كِبارٌ، صَغيرٌ ← صِغارٌ.
• فُعُل - typically from singulars with a long vowel: كِتابٌ ← كُتُبٌ، مَدينَةٌ ← مُدُنٌ، سَبيلٌ ← سُبُلٌ.
• فُعَل - the plural of the shape فُعْلَة, and here you may actually predict: غُرْفَةٌ ← غُرَفٌ، صورَةٌ ← صُوَرٌ. A handful of فَعْلَة nouns join them: دَوْلَةٌ ← دُوَلٌ.
• فُعّال - the plural of the human agent noun فاعِل: طالِبٌ ← طُلّابٌ، عامِلٌ ← عُمّالٌ، كاتِبٌ ← كُتّابٌ، ساكِنٌ ← سُكّانٌ.
• مَفاعِل - from four-letter singulars beginning with م: مَكْتَبٌ ← مَكاتِبُ، مَدْرَسَةٌ ← مَدارِسُ، مَسْجِدٌ ← مَساجِدُ.
• مَفاعيل - the same, when the singular has a long vowel before its last consonant: مِفْتاحٌ ← مَفاتيحُ، مَوْضوعٌ ← مَواضيعُ، مَشْروعٌ ← مَشاريعُ.
• أَفْعِلاء - human nouns and qualities shaped فَعيل: صَديقٌ ← أَصْدِقاءُ، طَبيبٌ ← أَطِبّاءُ، غَنِيٌّ ← أَغْنِياءُ.

4. Where prediction does work. The moulds are unpredictable for short, basic nouns. They are much more regular for longer, derived ones, and this is worth exploiting:

• A noun of four consonants or more almost always goes to مَفاعِل or مَفاعيل (or their twins فَعالِل / فَعاليل when the first letter is not م): صُنْدوقٌ ← صَناديقُ، مَلْعَبٌ ← مَلاعِبُ. The standing exception is the participles of lesson 9 - مُهَنْدِسٌ ← مُهَنْدِسونَ، مُعَلِّمَةٌ ← مُعَلِّماتٌ - which are long but take the sound plural. The rule of thumb: long singular, long plural, with ـا after the second letter.
• فاعِل naming a person usually goes to فُعّال or فَعَلَة: عامِلٌ ← عُمّالٌ، طالِبٌ ← طَلَبَةٌ. The sound plural stays available beside it (طالِبونَ، عامِلونَ).
• فَعيل naming a person or a human quality goes to أَفْعِلاء or فُعَلاء: كَريمٌ ← كُرَماءُ.
• فُعْلَة goes to فُعَل: نُقْطَةٌ ← نُقَطٌ.

Lesson 22 will show you the machinery behind all of this - the three-consonant root and the patterns poured over it. For now use these four tendencies as guesses, and check them.

5. A broken plural is an ordinary noun grammatically. This is the part beginners get wrong after learning ـونَ. A broken plural takes the ordinary singular-style endings ـٌ ـَ ـِ (with tanwīn when indefinite), takes الـ when definite, and never takes ـونَ or ـينَ on top:

• كُتُبٌ - كُتُبًا - كُتُبٍ, exactly like بَيْتٌ - بَيْتًا - بَيْتٍ

For agreement, a broken plural of male human beings behaves like a plural: الطُّلّابُ مُجْتَهِدونَ، الرِّجالُ كِرامٌ. A broken plural of things does something surprising, and lesson 11 is entirely about it - do not worry when you see a feminine singular adjective after a plural noun in the examples below.

6. Three of the nine take no tanwīn: the diptote flag. مَفاعِل، مَفاعيل and أَفْعِلاء belong to a class called المَمْنوع مِنَ الصَّرْف - “barred from full inflection”. Two things change:

• they never carry tanwīn: مَدارِسُ, not *مَدارِسٌ; مَفاتيحُ, not *مَفاتيحٌ
• in the genitive they take a fatḥa, not a kasra: دَرَسْتُ فِي مَدارِسَ كَثيرَةٍ

The second departure switches off the moment the word becomes definite with الـ or heads an إِضافَة (lesson 20): فِي المَدارِسِ، فِي مَدارِسِ المَدينَةِ - the ordinary kasra is back. The first never arises there, since a definite noun carries no tanwīn in any case. That is all you need at A1; lesson 41 gives the whole class and the rest of its members.

7. Collective nouns work the other way round. A small but very frequent group of nouns - plants, fruit, animals, small countable stuff - has its bare form standing for the kind or the mass, and adds ة to pick out one of them. The bare form is called اسْمُ الجِنْسِ الجَمْعِيّ, the ة-form اسْمُ الوَحْدَة:

• شَجَرٌ “trees, tree-stuff” - شَجَرَةٌ “a tree”
• تُفّاحٌ “apples” - تُفّاحَةٌ “an apple”
• سَمَكٌ “fish (as a kind or a dish)” - سَمَكَةٌ “a fish”
• بَقَرٌ “cattle” - بَقَرَةٌ “a cow”

Note the direction: the ة does not make it feminine-and-plural, it subtracts a unit from a mass. This is the opposite of what ة normally does, which is why it trips people up.

8. The bare collective takes singular agreement. Grammatically شَجَرٌ is a singular noun, however plural it feels in English, and masculine is the default: الشَّجَرُ جَميلٌ، السَّمَكُ لَذيذٌ، البَقَرُ كَبيرٌ. Never *الشَّجَرُ جَميلونَ. (Arabic also allows some collectives to be treated as feminine - هٰذا نَخْلٌ and هٰذِهِ نَخْلٌ are both attested - but stay with the masculine at A1.)

9. And the unit noun has its own plural. Once you have singled out one unit, you can count several of them, and then a real plural appears - broken for some words, sound ـاتٌ for others: شَجَرَةٌ ← أَشْجارٌ، سَمَكَةٌ ← أَسْماكٌ، تُفّاحَةٌ ← تُفّاحاتٌ. So each of these words has three forms, and each does a different job: the mass, one item, several items.

Forms & patterns

The nine high-yield moulds. Every plural here is given with its full ending, so you can see at a glance which ones refuse tanwīn:

The three endings, side by side, for an ordinary plural and a diptote one. Read the third row first - it is the only place the two systems really part company:

Collectives in their three forms:

Left out on purpose: the moulds فَواعِل، فُعَلاء، فَعالِلَة and a dozen rarer ones, and the distinction Arabic makes between a “plural of few” and a “plural of many”. You will meet them naturally, word by word.

Examples

Common mistakes

• كِتابونَ -> كُتُبٌ - the ending ـونَ belongs to male human beings, so a noun for a thing never takes it, whatever its plural looks like.
• الطُّلّابونَ -> الطُّلّابُ - and you certainly cannot use both systems at once. طُلّابٌ is already the plural; adding ـونَ plurals it twice.
• بَيْتاتٌ -> بُيوتٌ - ـاتٌ is not a general-purpose plural ending. Use the broken plural the word actually has; بَيْتٌ has بُيوتٌ and nothing else.
• مَدْرَساتٌ -> مَدارِسُ - the ending ة does not guarantee an ـاتٌ plural. (The word مُدَرِّساتٌ that you may have met is the plural of مُدَرِّسَةٌ “female teacher” - a different word.)
• أَقْلابٌ -> قُلوبٌ - you cannot copy a mould from a similar-looking word. قَلَمٌ takes أَفْعال and قَلْبٌ takes فُعول, and only the dictionary knows.
• مَدارِسٌ / مَفاتيحٌ -> مَدارِسُ / مَفاتيحُ - these moulds are مَمْنوعٌ مِنَ الصَّرْف and never take tanwīn, in any case.
• فِي مَدارِسِ كَثيرَةٍ -> فِي مَدارِسَ كَثيرَةٍ - an indefinite diptote takes fatḥa after a preposition. Note that the adjective is a normal word and keeps its kasra.
• فِي مَدارِسَ المَدينَةِ -> فِي مَدارِسِ المَدينَةِ - but as soon as the word is definite or heads an إِضافَة, the kasra comes back. The fatḥa rule is for the bare indefinite form only.
• أَكَلْتُ تُفّاحٌ كَبيرَةٌ. -> أَكَلْتُ تُفّاحَةً كَبيرَةً. - if you mean one apple you need the ة; the bare collective means apples in general.
• الشَّجَرُ جَميلونَ. -> الشَّجَرُ جَميلٌ. - a bare collective counts as singular, not plural, whatever it means.

Tips

• Learn every noun as a pair, out loud, from the first day: قَلَمٌ - أَقْلامٌ، بَيْتٌ - بُيوتٌ، مَدْرَسَةٌ - مَدارِسُ. Retro-fitting plurals onto a hundred nouns you learned bare is miserable.
• Recognise, do not derive. Your task with broken plurals at A1 is to hear مَفاتيحُ and think “plural of something”, not to produce it from مِفْتاحٌ by rule.
• Use the shape as a first guess: an أ in front plus a long ـا usually means a plural; ـا after the second consonant in a long word almost always does; a doubled middle consonant with ـُ in front (طُلّاب، عُمّال) is usually a plural of people - though not always, as تُفّاح shows.
• Length is your friend. Short words are wild; long words are tame. If the singular has four consonants, guess مَفاعِل / مَفاعيل and you will usually be right.
• Tie the diptote flag to the shape, not to a list: مَدارِسُ، مَفاتيحُ، أَصْدِقاءُ. If a plural looks like one of those three moulds, expect no tanwīn and fatḥa in the genitive.
• With collectives, ask yourself “the whole kind, or one of them?” before you write. That single question decides between سَمَكٌ and سَمَكَةٌ - and it is the same question in تُفّاح، بَقَر، بَيْض، وَرَق.
• Ignore for now how the adjective agrees with a plural of things. It is genuinely odd, and the very next lesson is about nothing else.
• Counting these plurals (three books, ten schools) has its own rules and its own lesson - 26. Until then, use them without a number in front.