ين

ـِينَ • (-īna) m

1. Oblique-case suffix—i.e. accusative-case (manṣūb) and genitive-case (majrūr)—used to pluralize masculine nouns and adjectives referring to people. In Classical Arabic, with full ʾiʿrāb, appears as ـِينَ‎ (-īna). Note that most masculine nouns and adjectives referring to people, especially shorter ones, are not pluralized in this fashion, but use a broken plural instead. Furthermore, non-human masculine nouns don't use this suffix, either forming a broken plural or using the "feminine" suffix ـَات‎ (-āt).
2. Oblique-case suffix used very occasionally to pluralize non-human nouns, including some that are feminine, such as سَنَة‎ (sana, “year”), accusative and genitive plural سِنِين‎ (sinīn).
3. -ty

• ـُونَ‎ (-ūna) (for the nominative case)

ـَيْنِ • (-ayni) m

1. Dual oblique suffix in Modern Standard Arabic. In Classical Arabic, with full ʾiʿrāb, appears as ـَيْنِ‎ (-ayni). The corresponding construct form is ـَيْ‎ (-ay).
2. Dual suffix in informal Arabic. The corresponding construct form is ـَيْ‎ (-ay).

• ـَانِ‎ (-āni) (for the nominative case)