The dual form in Arabic - Lesson 51

All nouns receive a special ending if there are two of them. When there are two of a noun, ان is added to the end of the noun to indicate that it is dual in the nominative case. For the accusative and genitive cases, we would have يْن (the ending of the dual will not usually be vowelled, so it will look like the suffix ending of the sound plural, but it will sound differently). The context will give you a hint about the number of the noun in question.