nunation
Noun
Meaning
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.orgSynonyms
Examples
In 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.
In written Arabic nunation is indicated by doubling the vowel diacritic at the end of the word.
They have also mostly lost the indefinite "nunation" and the internal passive.