Al-muqaddimah Al-ajurrumiyyah [on the Science of Arabic Grammar]

The Chapter on the NA‘T [and an explanation of the MA‘RIFAH (definite noun) and NAKIRAH (indefinite noun)]

The Na‘t[^53] is a Tābi‘ (follower) of the Man‘ūt in the latter’s Raf‘, Naṣb, Khafḍ, Ta‘rīf (definiteness) and Tankīr (indefiniteness). You say (for example):

قام زيدٌالعاقلُ              (Zayd,the intelligent , stood)

رأيت زيداًالعاقلَ           (I saw Zayd,the intelligent )

مررتُ بزيدٍالعاقلِ          (I passed by Zayd,the intelligent )

The Ma‘rifah is five things:

the Ism Muđmar (personal pronoun) like:             أنا  (I) and  أنت [you (masc. sing.)]

the Ism ‘Alam (proper name) like:                       زيد  (Zayd) and مكة  (Makkah)

the Ism Mubham (vague noun)[^54] like:                      هذا  [this (masc. sing.)],  هذه  [this (fem. sing.)] and  هؤلاء  [these (masc./fem. pl.)]

the Ism that has the Alif and Lām like:                   الرجل  (the man) and  الغلام  (the youngster/male servant)

What is Muḍāf (annexed) to one of these four[^55] .

The Nakirah is every Ism that is commonly (and equally) applied to (all the members of) its class such that no one (member) is to be distinguished by it (i.e. that Ism) at the exclusion of all the others. An easy way of understanding it is (to regard the Nakirah as) everything to which the Alif and Lām can be validly prefixed, like  الرَجُل  (the man) and  الغُلام  (the lad/servant).