Accusative case (abbreviated as ACC) is the grammatical case of nouns and pronouns that marks direct object of the verb. This term is used only in Colloquial/Modern Nûrlâm but rarely in Standard language where it is called Objective case (see below). Moreover, objective case if formed differently for nouns and pronouns. As the objective/accusative form of pronouns is irregular, please consult articles about pronouns or cases for further information.
The term Objective case is used because personal pronouns have distinct form when used as objects of sentence. Subjective form is considered Nominative and objective form is called Objective, however they are completely different and still join the verb into different slots.
Nouns in objective/accusative case are formed by suffix -ish, but this suffix is considered archaic. Even in Standard language nouns lost this ending in favor of same null-ending as Nominative case. However suffix -ish may be still used for objective nouns if the sentence is too complex or has non-standard free word order (for example in poetry).
Nouns have completely lost special ending of Accusative/Objective case in colloquial speech. However personal pronouns kept it. Some subdialects even took objective form of personal pronouns as the default nominative. Moreover they have tendency to add old noun's objective suffix -ish to them (as well as other case suffixes). But there are a lot of irregularities in pronouns' case form, so consult corresponding pages.