Noun
The use of a suffix ("-n") signifying a lack of syntactical definiteness of the noun or adjective in standard Arabic. It is written as a diacritic over the final letter.
نهر (nahr-un, “a river”)
ملك (malik-un, “a king”)
The use of a suffix ("-n") in dual forms in Akkadian.
Source: en.wiktionary.orgIn the later stages of Akkadian the mimation (word-final -m) - along with nunation (dual final "-n") - that occurs at the end of most case endings has disappeared, except in the locative. Source: Internet
In written Arabic nunation is indicated by doubling the vowel diacritic at the end of the word. Source: Internet
They have also mostly lost the indefinite "nunation" and the internal passive. Source: Internet