What is Tanween in Arabic?

The tanween (or nunation) in Arabic (also transliterated as tanwin/tenwin) has to do with the sound ن noon. To be precise, it is an acoustic ن (i.e. said but not written). This ن is added to the end of nouns (and adjectives). Only nouns (and adjectives) get tanween, but not all nouns. Certain nouns; all types of pronouns, which are classified as nouns in Arabic; verbs; and particles (e.g. prepositions, words of negation, words of interrogation, conjunctions) do not get it. Generally, the tanween is used: (1) to distinguish nouns from other parts of speech and (2) to indicate that the noun with which it is used is indefinite نَكِرَةٌ; that is, it does not refer to a specific entity (thing, person). If we define the noun by adding the definite article to it (i.e., الْـ), the tanween is removed and replaced by the corresponding short vowel: fatha, dhamma, or kasra.

Types of Tanween:

For each short vowel in Arabic, there is a corresponding tanween mark that is added only to the end of words. For the dhamma, it is tanween al-dhamma marked by double dhammas ــٌ, and it is pronounced as un. For the fatha, it is tanween al-fatha marked by double fathas ــً, and it is pronounced as an. For the kasra, it is tanween al-kasra marked by double kasras ــٍ, and it is pronounced as in, hence كِتَابٌ kitab-un ‘a book’, كِتَابًا kitab-an, and كِتَابٍ kitab-in; بَيْتٌ bayt-un ‘a house’, بَيْتًا bayt-an, and بَيْتٍ bayt-in; شَجَرَةٌ shajarat-un ‘a tree’, شَجَرَةً shajarat-an, and شَجَرَةٍ shajarat-in and so forth. 

الْكَسْرَة		الْفَتْحَة		الضَّمَّة
بٍ	بِ	بًا	بَ	بٌ	بُ
ءٍ	ءِ	ءً / ءًا	ءَ	ءٌ	ءُ
لٍ	لِ	ـلًا	لَ	لٌ	لُ
ـةٍ	ـةِ	ـةً	ـةَ	ـةٌ	ـةُ
ـهٍ	ـهِ	ـهًا	ـهَ	ـهٌ	ـهُ
With tanween al-fatha, alif is added after the tanween (not before), except with ـة (taa marbuta) and certain types of hamzah. When we stop/pause on the word that has tanween, especially at the end of sentences (or with single words), the acoustic ن, i.e. tanween, is removed, and the last letter of the word will be saakin, i.e. has sukuun over it. And sukuun means the absence of a short vowel. Hence, كِتَابٌ kitab-un, كِتَابًا kitab-an, and كِتَابٍ kitab-in become كِتَاب kitab.

ٍ	ً	ٌ
كِتَابٍ	كِتَابًا	كِتَابٌ      a book
شَيْخٍ	شَيْخًا	شَيْخٌ   an old man
شَيْءٍ	شَيْئًا	شَيْءٌ       a thing
تُفَّاحَةٍ	تُفَّاحَةً	تُفَّاحَةٌ    an apple
مَاءٍ	مَاءً	مَاءٌ           water
خَيْرٍ	خَيْرًا	خَيْرٌ    a good deed
بَيْتٍ	بَيْتًا	بَيْتٌ       a house
جُزْءٍ	جُزْءًا	جُزْءٌ      a section
طَبِيبٍ	طَبِيبًا	طَبِيبٌ a physician

tanween Assignment:

The tanween is always added to the end of the indefinite noun. The position of this noun in the sentence determines the type of tanween it gets. If the indefinite noun is a subject فَاعِل, a topic مُبْتَدَأ, or a predicate خَبَر, it gets tanween al-dhamma. If the indefinite noun is an object مَفْعُول (among other positions), it gets tanween al-fatha. And if it is after a preposition, it gets tanween al-kasra.

tanween al-dhammah
(A) tanween al-dhamma at the end of the indefinite noun means that this noun is مَرْفُوع ‘in the nominative case’. (B) In (1) and (4), the indefinite noun is a predicate خَبَر to the topic الْمُبْتَدَأ before it.  (C) In (3) and (6), the indefinite noun is a topic مُبْتَدَأ. Note that when the topic مُبْتَدَأ is indefinite نَكِرَة, it occurs after the predicate خَبَر. (D) In (2) and (5), the indefinite nouns is a subject فَاعِل of the verb الْفِعْل which precedes it.	(1) هَذَا مِفْتَاحٌ. This is a key (2) خَرَجَتْ بِنْتٌ مِنَ الْغُرْفَةِ. A girl came out of the room (3) فِي الْمَدِينَةِ مَلْعَبٌ. There is a stadium in the city (4) السَّيَّارَةُ جَدِيدَةٌ. The car is new (5) نَبَحَ كَلْبٌ. A dog barked (6) أَمَامَ الْبَيْتِ دُكَّانٌ. There’s a shop in front of the house
tanween al-fatha
(A) tanween al-fatha at the end of the indefinite noun means that this noun is مَنْصُوب ‘in the accusative case’. (B) Since they represent the receiver of the action, each noun in these examples is مَفْعُول. Note that there are other positions in which the noun is مَنْصُوب. This will be explained in future lessons. (C) جَدِيْدةً and جَدِيْدًا in (3) and (5) are adjectives, and they follow the preceding noun in gender and case, so they are assigned tanween.	(1) وَجَدْتُ مِفْتَاحًا فِي الشَّارِعِ. I found a key in the street (2) رَأَيْتُ بِنْتًا فِي الْحَدِيْقَةِ. I saw a girl in the garden (3) اِشْتَرَى أَبِي سَيَّارَةً جَدِيْدَةً. My father bought a new car (4) قَتَلَ الصَّيَّادُ أَسَدًا. The hunter killed a lion (5) فَتَحَ التَّاجِرُ دُكَانًا جَدِيْدًا. The businessman opened a new shop
tanween al-kasrah
(A) tanween al-kasra at the end of the indefinite noun means that this noun is مَجْرُور ‘in the genitive case’. (B) Since it is preceded by a preposition, every noun in these examples is مَجْرُور. (C) in (2) and (3), صَغِيرٍ and جَدِيدٍ follow the noun in gender and tanween (i.e. case).	(1) يَأكُلُ الطِّفْلُ بِمِلْعَقَةٍ. The child eats with a spoon (2) أَسْكُنُ فِي بَيْتٍ صَغِيْرٍ. I live in a small house (3) كَتَبْتُ بَقَلَمٍ جَدِيْدٍ. I wrote with a new pen (4) يَبْحَتُ الطَّالِبُ عَنْ عَمَلٍ. The student is looking for a job (5) نَامَ الْمُسَافِر تَحْتَ شَجَرَةٍ. The traveller slept under a tree

Replacing the tanween with Short Vowels:

The tanween at the end of indefinite nouns changes to its corresponding short vowel if these nouns are made definite. As mentioned above, this means that tanween is a marker for indefiniteness عَلَامَةُ التَّنْكِيرِ.

	اِسْم مَعْرِفَة definite noun	اِسْم نَكِرَة indefinite noun
(A) With the definite nouns, short vowels (fatha, Dhamma, or kasra) replace the tanween. (B) The indefinite nouns are made definite by prefixing (adding) the definite article الْـto them. (C) Note that in (4), when the indefinite مُبْتَدَأ is made definite, it must be moved to the beginning of the sentence	رَأَيْتُ الْبِنْتَ فِي الْحَدِيْقَةِ. هَذَا الْمِفْتَاحُ لِمُحَمَّدٍ. نَامَ الْمُسَافِرُ تَحْتَ الشَّجَرَةِ. الدُّكَّانُ أَمَامَ اليْتِ. يَأْكُلُ الطِّفْلُ بِالْمِلْعَقةِ. وَجَدْتُ الْمِفْتَاحَ فِي الشَّارِعِ.	(1) رَأَيْتُ بِنْتًا فِي الْحَدِيْقَةِ (2) هَذَا مِفْتَاحٌ. (3) نَامَ الْمُسَافِرُ تَحْتَ شَجِرَةٍ. (4) أَمَامَ الْبَيْتِ دُكَّانٌ. (5) يَأْكُلُ الطِّفْلُ بِمِلْعَقَةٍ. (6) وَجَدْتُ مِفْتَاحًا فِي الشَّارِعِ.

tanween and shadda:

shadda means two consecutive consonants. One of the consonants is saakin (i.e., has a sukuun over it), and the other is mutaharrik (i.e., has a short vowel over it). They are blended together and written as one consonant with a shadda and the short vowel of second consonant. At the end of words (namely, nouns and adjectives) this short vowel is replaced with the corresponding tanween mark when a word is assigned the tanween (as determined by the grammar), as in the following tables: 

(1) shadda with tanween al-dhamma

فَ + نْ + نٌ	فَنٌّ	an art
جَ + دْ + دٌ	جَدٌّ	a grandfather
حَ + رْ + رٌ	حَرٌّ	heat
حَ + ظْ + ظٌ	حَظٌّ	luck
فَ + كْ + كٌ	فَكٌّ	jaw, dismantling
جِ + نْ + نٌ	جِنٌّ	demons
شُ + حْ + حٌ	شُحٌّ	stinginess
رَ + بْ + بٌ	رَبٌّ	a lord
غَ + شْ + شٌ	غَشٌّ	cheating
فَ + ظْ + ظٌ	فَظٌّ	rude

(2) shadda with tanween al-fatha

فَ + خْ + خً + ا	فَخًّا	a trap
عِ + زْ + زً + ا	عِزًّا	glory
رَ + شْ + شً + ا	رَشًّا	spraying
قِ + طْ + طً + ا	قِطًّا	a cat
شَ + طْ + طً + ا	شَطًّا	a shore
حَ + قْ + قً + ا	حَقًّا	a right
بُ + نْ + نً + ا	بُنًّا	coffee
صَ + فْ + فً + ا	صَفًّا	a line / queue
عَ + مْ + مً + ا	عَمًّا	an uncle
رَ + جْ + جً + ا	رَجًّا	shaking

(3) shadda with tanween al-kasra 

خَ + سْ + سٍ	خَسٍّ	lettuce
لِ + صْ + صٍ	لِصٍّ	a thief
خَ + طْ + طٍ	خَطٍّ	handwriting
رَ + فْ + فٍ	رَفٍّ	a shelf
صَ + كْ + كٍ	صَكٍّ	a check
فَ + مْ + مٍ	فَمٍّ	a mouth
كُ + لْ + لٍ	كُلٍّ	all
عُ + شْ + شٍ	عُشٍّ	a nest
مَ + طْ + طٍ	مَطٍّ	stretching
شَ + قْ + قٍ	شَقٍّ	a crack