In short

Arabic sorts every noun and every adjective into one of two boxes, مُذَكَّر and مُؤَنَّث. There is no third box and no opting out. Nothing at all marks the masculine - it is just the bare word: وَلَدٌ، كِتابٌ، كَبيرٌ. The feminine is the marked member of the pair, and in the great majority of words the mark is a single letter sitting at the end, ة, called التّاءُ المَرْبوطَةُ. Put it on طالِبٌ and you have طالِبَةٌ; put it on كَبيرٌ and you have كَبيرَةٌ.

Two facts make this less mechanical than it sounds. A short list of very common nouns is feminine with no mark whatsoever - شَمْسٌ، أَرْضٌ، يَدٌ - and a shorter list of nouns ends in ة while being masculine - خَليفَةٌ، حَمْزَةُ. Both lists are vocabulary, not logic, and both are worth an hour of memorising now. Gender also refuses to stay put on the noun: it spreads to the adjective, the pronoun, the demonstrative and the verb, so one wrong guess about a noun surfaces as four wrong words in the sentence.

The rule

1. The masculine is unmarked. Do not look for a masculine ending, because there is none. A noun or adjective with no feminine marker is masculine unless it belongs to one of the memorised lists in point 4:

بَيْتٌ، كِتابٌ، قَلَمٌ، وَلَدٌ، بابٌ، طالِبٌ، كَبيرٌ، جَديدٌ، جَميلٌ

The tanwīn on the end of these words says “indefinite” (lesson 4). It says nothing about gender.

2. The feminine marker you will meet nine times out of ten is ة. It attaches to the bare masculine form and does not change anything before it:

• طالِبٌ -> طالِبَةٌ، مُدَرِّسٌ -> مُدَرِّسَةٌ، مُهَنْدِسٌ -> مُهَنْدِسَةٌ، طَبيبٌ -> طَبيبَةٌ
• كَبيرٌ -> كَبيرَةٌ، صَغيرٌ -> صَغيرَةٌ، جَديدٌ -> جَديدَةٌ، مُجْتَهِدٌ -> مُجْتَهِدَةٌ

Note the fatḥa on the letter in front of the ة: مُدَرِّسَةٌ, never *مُدَرِّسْةٌ. The vowel before a ة is always an a - either the short fatḥa, as here, or the long ā written with an alif: فَتاةٌ، حَياةٌ.

Careful, though: ة is not a switch you may flip on any noun to make a female version. With people and animals it usually does exactly that. Elsewhere it is simply part of the word, and the pair of words may not be related in meaning at all: مَكْتَبٌ is a desk or an office, while مَكْتَبَةٌ is a library. Both are ordinary nouns; only the second is grammatically feminine.

3. Two further feminine endings. They are much rarer than ة, but they are not exotic - you will meet them in your first month, in colours and in a few everyday nouns.

• ـاء, called أَلِفُ التَّأْنيثِ المَمْدودَةُ: صَحْراءُ (desert), حَمْراءُ (red, feminine), بَيْضاءُ (white, feminine), خَضْراءُ (green, feminine).
• ـى, called أَلِفُ التَّأْنيثِ المَقْصورَةُ: كُبْرى (biggest, feminine), صُغْرى (smallest, feminine), ذِكْرى (memory, anniversary), بُشْرى (good news), الدُّنْيا (the world - after a yāʾ this same ending is written with a plain alif; the pronunciation guide’s hamza lesson has the rule).

Two practical warnings. First, these words carry no tanwīn: you write صَحْراءُ and حَمْراءُ, not *صَحْراءٌ. Words ending in a feminine ـاء or ـى belong to a class that refuses tanwīn altogether, and their masculine partners are in it too - أَحْمَرُ، أَبْيَضُ، أَكْبَرُ end in a bare ḍamma however ordinary they look, so *قَميصٌ أَبْيَضٌ is wrong; lesson 41 explains why, and until then simply do not write it. Second, not every ـاء is this ending. In ماءٌ (water) and سَماءٌ (sky) the ء is part of the root, so those words behave normally and do take tanwīn - and ماءٌ, in spite of its shape, is masculine.

4. The unmarked feminines: a list to memorise. These nouns carry no feminine marker and are feminine anyway. There is no rule behind most of them, and there are not many, so learn them as a block. They fall into four groups:

• female beings: أُمٌّ، بِنْتٌ، أُخْتٌ, and women’s names with no ة - مَرْيَمُ، زَيْنَبُ، هِنْدُ، سُعادُ
• a fixed set of everyday nouns: شَمْسٌ، نارٌ، أَرْضٌ، دارٌ، ريحٌ، حَرْبٌ، نَفْسٌ، سِنٌّ
• body parts that come in pairs: يَدٌ، عَيْنٌ، رِجْلٌ، أُذُنٌ، قَدَمٌ. This is a strong tendency rather than a law, and it still pays for itself: most paired organs are feminine, and the single ones are masculine - أَنْفٌ، رَأْسٌ، فَمٌ، لِسانٌ، قَلْبٌ. The exceptions to note are حاجِبٌ (eyebrow) and مِرْفَقٌ (elbow), which come in pairs and are masculine anyway.
• names of countries and cities: مِصْرُ، دِمَشْقُ، بَغْدادُ، القاهِرَةُ، بَيْروتُ. City names are reliably feminine. A few country names go the other way and are treated as masculine - العِراقُ، السّودانُ، المَغْرِبُ، لُبْنانُ - so learn a country’s gender with its name.

5. The reverse trap: masculine nouns that end in ة. A ة on the end is strong evidence of feminine gender, not proof of it. Two groups end in ة while referring to men, and they take masculine agreement throughout:

• titles and intensive descriptions: خَليفَةٌ (caliph), عَلّامَةٌ (great scholar), رَحّالَةٌ (great traveller). The ة here is an old intensifier - it makes the description stronger, not female.
• men’s given names: حَمْزَةُ، أُسامَةُ، طَلْحَةُ، مُعاوِيَةُ. These are men, so everything that agrees with them is masculine: حَمْزَةُ كَريمٌ, never *حَمْزَةُ كَريمَةٌ.

The lesson to take from points 4 and 5 together: gender is a property of the word, and the ending is a very good clue to it, not a definition of it. When the two disagree, meaning wins.

6. Gender surfaces in four places. The noun by itself rarely gives you trouble. What gives you trouble is everything that has to match it:

• the adjective follows its noun and copies its gender: وَلَدٌ صَغيرٌ / بِنْتٌ صَغيرَةٌ، بَيْتٌ جَديدٌ / سَيّارَةٌ جَديدَةٌ. Full details in lesson 8.
• the pronoun: هُوَ for a masculine noun, هِيَ for a feminine one - and this holds for objects too, so a book is هُوَ and a car is هِيَ. Lesson 6.
• the demonstrative: هٰذا كِتابٌ / هٰذِهِ مَدْرَسَةٌ. Lesson 13.
• the verb: the present-tense prefix changes, يَكْتُبُ for he and تَكْتُبُ for she - الوَلَدُ يَقْرَأُ / البِنْتُ تَقْرَأُ. Lessons 14 and 19.

This is why the memorised lists matter so much. Getting شَمْسٌ wrong is not one mistake; it is a mistake repeated in every adjective, pronoun and verb that points back at it.

7. How ة is pronounced. The letter is a ه wearing the two dots of a ت, and it behaves like both, depending on what follows it.

• In pause - when the word ends the utterance and you drop the case ending, which is what people actually do in speech, and what the pronunciation guide calls the pausal form - the ت is not heard at all. You hear only the fatḥa in front of it: مَدينَة.
• With a case ending or a tanwīn on it, the ت is fully pronounced, and the ending follows it: مَدينَةٌ، مَدينَةً، مَدينَةٍ. This is one reason the vowel marks in this path are printed on every word - they are the only thing that tells you whether the ت is spoken.
• Before an attached pronoun, the ة is rewritten as a plain ت and pronounced: سَيّارَةٌ becomes سَيّارَتي; مَدينَةٌ becomes مَدينَتُهُ. Lesson 7.
• As the first term of an إِضافَة, the ت is always pronounced, even at a pause, because the word is not finished: مَدينَةُ القاهِرَةِ، سَيّارَةُ المُدَرِّسِ، غُرْفَةُ الطَّعامِ. This is the classic giveaway that a speaker has understood the construction (lesson 20).

8. Writing ة correctly. It is always word-final; it never begins or sits inside a word, and it never joins to a following letter. The two dots are obligatory: مَدْرَسَةٌ is a school, مَدْرَسَه is nothing. Leaving the dots off is a widespread habit in casual typing and an outright error in written Arabic, so form the habit now. Note also that the accusative tanwīn on a ة takes no extra alif: مَدينَةً, not *مَدينَةًا (lesson 4).

9. Flagged, not taught: plurals. Everything above is about the singular. Arabic plurals do something that will look bizarre from here - the plural of a non-human noun is treated as feminine singular, so الكُتُبُ جَديدَةٌ is correct for “the books are new”, with a feminine adjective on a masculine noun. Do not try to reason it out now, and do not let it shake the singular rules. Lessons 9 to 15 build it up properly.

Forms & patterns

The three feminine endings, each against its masculine partner:

Ordinary pairs built with ة - nouns for people, then adjectives:

A few pairs use two unrelated words instead of an ending:

Feminine without any marker - the list to memorise:

Masculine in spite of the ة:

Where the gender becomes visible:

The ة and its four environments:

Examples

Common mistakes

• بِنْتٌ جَميلٌ -> بِنْتٌ جَميلَةٌ - the noun carries no ة, but it is feminine, and the adjective must show that. Never let the shape of the noun decide the adjective for you.
• الشَّمْسُ حارٌّ -> الشَّمْسُ حارَّةٌ - شَمْسٌ heads the memorised list of unmarked feminines. The same goes for أَرْضٌ، نارٌ، ريحٌ، حَرْبٌ.
• هٰذا بِنْتٌ -> هٰذِهِ بِنْتٌ - the demonstrative agrees just as the adjective does, so an unmarked feminine noun still takes هٰذِهِ.
• الخَليفَةُ العادِلَةُ (of a man) -> الخَليفَةُ العادِلُ - خَليفَةٌ ends in ة and is masculine. The ة on it is an intensifier, not a gender mark.
• أُسامَةُ ذَهَبَتْ إِلَى السّوقِ -> أُسامَةُ ذَهَبَ إِلَى السّوقِ - a man’s name in ة takes a masculine verb. Meaning outranks spelling every time.
• مَدْرَسَه -> مَدْرَسَةٌ - write the two dots. ة and ه are different letters, and dropping the dots turns a school into nothing at all.
• صَحْراءٌ واسِعَةٌ -> صَحْراءُ واسِعَةٌ - a word ending in the feminine ـاء takes no tanwīn. The single ḍamma is its full and correct ending.
• كُبْرًى -> كُبْرى - the same applies to the feminine ـى: no tanwīn, and nothing is written above the alif maqṣūra.
• مِصْرُ جَميلٌ -> مِصْرُ جَميلَةٌ - city names, and most country names, are feminine, however masculine the word looks.
• مَدينَه القاهِرَةِ -> مَدينَةُ القاهِرَةِ - in an إِضافَة the first word is not at a pause, so its ة is written properly and its ت is pronounced, followed by the case ending.

Tips

• Never store a noun on its own. Store it with a matching adjective - شَمْسٌ حارَّةٌ، بَيْتٌ كَبيرٌ - and the gender comes back with the word instead of being guessed at.
• The exception list is genuinely short. Fifteen or so unmarked feminines and half a dozen masculines in ة cover almost everything you will meet before B1. Spend one sitting on them.
• Use the body rule as a real shortcut: if the organ comes in a pair it is feminine, if there is only one of it, it is masculine. It works often enough to be worth trusting.
• When you meet a new word ending in ة, ask what it refers to before you assume. A person? Then the ة almost certainly marks a woman. A man, or a title of a man? Then it does not.
• Say every ة word twice out loud: once in pause and once with its ending. That single habit builds the reflex you need for the إِضافَة later.
• If a dictionary entry looks masculine but a text keeps giving it feminine adjectives, believe the text - you have found one of the unmarked feminines.
• Ignore plurals completely for now, including anything you notice about feminine adjectives on plural objects. That belongs to lessons 9 to 15 and will only muddle the singular.
• Do not hunt for logic in شَمْسٌ or حَرْبٌ. Gender assignment for non-living things is history, not meaning, and a learner’s time is better spent on the list than on the reason.