Broken Plural
The two previous plurals we dealt with were called sound masculine plural and sound feminine plural. This is because they kept their singular form intact in the plural form (except for the final vowel, which does not count anyway as it always changing). There was only the suffixing of ون or ات.
Now, why is the broken plural called so? You have correctly guessed, am sure: it does not keep its singular form intact. The following examples prove our point.
| Plural | Singular |
|---|---|
| كُتُب | كِتَاب |
| أَقْلام | قَلَم |
| فُصُول | فَصْل |
| حَدائِق | حَديقة |
| جُزُر | جَزيرة |
Let us analyse the first example. When كتاب becomes كتب, first it loses its ا. Second, there is a major change in vowelling; in fact all the non-final vowels changed. You will not be able to "extract" the singular form كتاب from the plural form كتب, as you will be for مهندس from مهندسون.
In the second example, letters are added at the beginning and in between the initial letters, with changes in most vowels.
The third example sees the addition of only one letter to the singular form. Again all non-final vowels underwent a change.
The fourth example is quite complicated. One letter is added (ا), one is substituted with another (ي becomes ئـ), and the last one (ة) is omitted.