In Arabic grammar, the permanent case (الحالة الدائمة) is the case that a noun retains when it is not connected to another word by a preposition or construct. It is also known as the nominative case (الحالة الاسمية). The permanent case is used for the following:
The subject of a verb (فاعل): The subject of a verb is the noun or pronoun that performs the action of the verb. It is always in the permanent case. For example, in the sentence "الطلاب يدرسون" (The students are studying), the noun "الطلاب" (the students) is the subject of the verb "يدرسون" (are studying) and is therefore in the permanent case.
The predicate nominative (خبر): The predicate nominative is a noun or pronoun that identifies or describes the subject. It is also in the permanent case. For example, in the sentence "محمد هو المعلم" (Muhammad is the teacher), the noun "المعلم" (the teacher) is the predicate nominative and is therefore in the permanent case.
The vocative (منادى): The vocative is a noun or pronoun that is used to address someone directly. It is also in the permanent case. For example, in the sentence "يا محمد، تعال هنا" (Muhammad, come here), the noun "محمد" (Muhammad) is the vocative and is therefore in the permanent case.
The permanent case is the most common case in Arabic. It is the default case for nouns that are not connected to other words by prepositions or constructs.
Here are some examples of nouns in the permanent case:
الكتاب (the book)
الطاولة (the table)
المدرسة (the school)
المعلم (the teacher)
الطالبة (the student)
I hope this helps! Let me know if you have any other questions.