Indeclinable nouns and adjectives end in alif maqsuura with two fathas representing nunation. For example, مُسْتَشْفَى Often the nunation is not pronounced, but it will be written in a fully-vocalized text. Indeclinables do not show case, so the two fathas do not represent a case ending. If the word is made definite, the two fathas disappear – المستشفى Again, no case marker will be added.
Therefore, an indeclinable is either indefinite with nunation (indicated by two fathas) or definite without nunation (no fathas). No case marker will ever be put on a masculine singular indeclinable.
All defective verbs in Forms II-X have passive participles which are indeclinables. In fact, مُسْتَشفى is the passive participle of the Form X verb إسْتَشفى . Since they can be used as nouns and adjectives, indeclinables can be made feminine and can take sound human plurals, masculine and feminine. We will use the passive participle of the verb سمَّى to name” in the examples below.
The passive participle of سمّى is مُسَمَّى “named.” “The boy is named Sami” is الولدُ
مُسَمَّى سامي. Here مُسَمَّى is the predicate of an equational sentence. Therefore, it should be in the nominative case. However, indeclinables do not show case. The two fathas indicate only the presence of nunation because the word is indefinite. (By the way, very, very often, the nunation is not pronounced in these words. So what you will usually hear is “musamma” instead of “mussamman.”)
“The boy named Sami is here” is الولدُ المُسَمّى سامي موجودٌ هنا. Now . المسمى does not have nunation because it is definite. It will show no case marker at all.
“The girl is named Samiira” is البنتُ مُسَمَاةٌ سميرة The alif maqsuura is changed to an alif in the feminine. The alif is followed by a ة . Since words that end in ة have regular case endings, the two dhammas appear over the ة in our sentence. “The girl named Samiira” is البنتُ المسماة سميرة
The masculine sound plural of مسمَّى is مُسَمَّوْنَ in the nominative and مُسَمَّيْنَ in the genitive/accusative. The plurals keep a fatha as a stem vowel and thus they are pronounced with diphthongs.
The feminine sound plural is مُسَمَّياتٌ and will take the case endings of any sound feminine plural. Many indeclinables which are passive participles of derived verbs will have feminine sound plurals, whether they are referring to human beings or not. For example, the plural of مُسْتَشفى is مُسْتَشْفَياتٌ .
Indeclinables can be made dual. They are all regular in the dual. For مُسمَّى, the nominative dual form is مُسَمَّيانِ and the genitive/accusative is مُسَمَّيَيْنِ. In the feminine the forms are مُسَمَّيتانِ and مُسَمَّيتيْنِ .
When a masculine singular indeclinable has a pronoun suffix attached, the alif maqsuura becomes an alif as in “his hospital” مستشفاهُ .
Some indeclinables are not passive participles of derived verbs. مَعْنىً and مَقْهًى are examples. These two nouns happen to be place nouns. Their plurals are مَعانٍ and مقاهٍ , respectively. These two plurals are defectives.
A very small number of indeclinables end in an alif instead of an alif maqsuura if the last radical of the word is a waaw and the word has only the three letters of its root. عصًا “stick” is the most common example.
Not all words that end in alif maqsuura are indeclinables. For example, فَتْوى and كبرى These words differ from indeclinables only in that they never take the two fathas. They never show case or nunation.
So Why Is This Important?
Since the two fathas so frequently referred to above are usually never pronounced anyway, you can pretty much forget them. However, you need to be aware of the following:
1. Passive participles of defective verbs in Forms II-X are indeclinables.
2. The feminine singular form of these indeclinables looks funny – as in مُسَماة .
3. When these words (and any other noun ending in alif maqsuura) have a possessive pronoun attached, the alif maqsuura becomes an alif –مستشفاهُ ُ
Item 3 above also applies to words like فتوى which are not indeclinables. So you may see فتواهُ “his fatwa”. (A fatwa is a legal opinion delivered concerning a point of Islamic law.)