Case

The accusative case (abbreviated ACC) of a noun is the grammatical case used to mark the direct object of a transitive verb. The same case is used in many languages for the objects of (some or all) prepositions. It is a noun that is having something done to it, usually joined (such as in Latin) with the nominative case.

In the sentence I see the car, the noun phrase the car is the direct object of the verb "see". In English, which has mostly lost the case system, the definite article and noun – "the car" – remain in the same form regardless of the grammatical role played by the words. One can correctly use "the car" as the subject of a sentence also: "The car is parked here."

In a declined language, the morphology of the article or noun changes in some way according to the grammatical role played by the noun in a given sentence. For example, in German, one possible translation of "the car" is der Wagen. This is the form in nominative case, used for the subject of a sentence. If this article/noun pair is used as the object of a verb, it (usually) changes to the accusative case, which entails an article shift in German – Ich sehe den Wagen. In German, masculine nouns change their definite article from der to den in the accusative case.

In grammar, the case of a noun or pronoun indicates its grammatical function in a greater phrase or clause; such as the role of subject, of direct object, or of possessor. While most languages distinguish cases in some fashion, it is only customary to say that a language has cases when these are codified in the morphology of its nouns — that is, when nouns change their form to reflect their case. (Such a change in form is a kind of declension, hence a kind of inflection.) Cases are related to, but distinct from, thematic roles such as agent and patient; while certain cases in each language tend to correspond to certain thematic roles, cases are a syntactic notion whereas thematic roles are a semantic one.

Cases are not very prominent in modern English, except in its personal pronouns (a remnant of the more extensive case system of Old English). For other pronouns, and all nouns, adjectives, and articles, case is indicated only by word order, by prepositions, and by the clitic -'s.

Taken as a whole, English personal pronouns are typically said to have three morphological cases: the nominative case (such subjective pronouns as I, he, she, we), used for the subject of a finite verb and sometimes for the complement of a copula; the accusative/dative case (such objective pronouns as me, him, her, us), used for the direct or indirect object of a verb, for the object of a preposition, for an absolute disjunct, and sometimes for the complement of a copula; and the genitive case (such possessive pronouns as my/mine, his, her(s), our(s)), used for a grammatical possessor. That said, these pronouns often have more than three forms; the possessive typically has both a determiner form (such as my, our) and a distinct independent form (such as mine, ours). Additionally, except for the interrogative personal pronoun who, they all have a distinct reflexive or intensive form (such as myself, ourselves).

While not very prominent in English, cases feature much more saliently in many other Indo-European languages, such as Latin, Greek, German, Sanskrit, and Russian. Historically, the Indo-European languages had eight morphological cases, though modern languages typically have fewer, using prepositions and word order to convey information that had previously been conveyed using distinct noun forms. The eight historic cases are as follows, with examples:

The nominative case, which corresponds to English's subjective case, indicates the subject of a finite verb:
We went to the store.

The accusative case, which together with the dative and ablative cases (below) corresponds to English's objective case, indicates the direct object of a verb:
The clerk remembered us.

The dative case indicates the indirect object of a verb:
The clerk gave us a discount.

The ablative case indicates movement from something, and/or cause:
The victim went from us to see the doctor.
He was unhappy because of depression.

The genitive case, which corresponds to English's possessive case, indicates the possessor of another noun:
Our citizens are proud of our country.

The vocative case indicates an addressee:
You there, are you O.K.?

The locative case indicates a location:
We live in China.

The instrumental case indicates an object used in performing an action:
We wiped the floor with it.

All of the above are just rough descriptions; the precise distinctions vary from language to language, and are often quite complex. Case is arguably based fundamentally on changes to the noun to indicate the noun's role in the sentence. This is not how English works, where word order and prepositions are used to achieve this; as such it is debatable whether the above examples of English sentences can be said to be examples of 'case' in English

Case and linguistic typology
Main article: Morphosyntactic alignment

Languages are categorized into several case systems, based on their morphosyntactic alignment — how they group verb agents and patients into cases:

Nominative-accusative (or simply accusative): The argument (subject) of an intransitive verb is in the same case as the agent (subject) of a transitive verb; this case is then called the nominative case, with the patient (direct object) of a transitive verb being in the accusative case.

Ergative-absolutive (or simply ergative): The argument (subject) of an intransitive verb is in the same case as the patient (direct object) of a transitive verb; this case is then called the absolutive case, with the agent (subject) of a transitive verb being in the ergative case.

Ergative-accusative (or tripartite): The argument (subject) of an intransitive verb is in its own case (the intransitive case), separate from that of the agent (subject) or patient (direct object) of a transitive verb (which is in the ergative case or accusative case, respectively).

Active-stative (or simply active): The argument (subject) of an intransitive verb can be in one of two cases; if the argument is an agent, as in "He ate," then it is in the same case as the agent (subject) of a transitive verb (sometimes called the agentive case), and if it's a patient, as in "He tripped," then it is in the same case as the patient (direct object) of a transitive verb (sometimes called the patientive case).

Trigger: One noun in a sentence is the topic or focus. This noun is in the trigger case, and information elsewhere in the sentence (for example a verb affix in Tagalog) specifies the role of the trigger. The trigger may be identified as the agent, patient, etc. Other nouns may be inflected for case, but the inflections are overloaded; for example, in Tagalog, the subject and object of a verb are both expressed in the genitive case when they are not in the trigger case.
The following are systems that some languages use to mark case instead of, or in addition to, declension:

Positional: Nouns are not inflected for case; the position of a noun in the sentence expresses its case.

Adpositional: Nouns are accompanied by words that mark case.

Some languages have very many cases; for example, Finnish has eighteen (see Finnish language noun cases), Hungarian has eighteen and Tsez can even be analyzed as having 126 cases.

John Quijada's constructed language Ithkuil has 81 noun cases, and its descendent Ilaksh has a total of 96 noun cases.[1][2]

In Indo-European languages, each case often contains several different endings, some of which may even be derived from different roots. An ending is chosen depending on gender, number, whether the word is a noun or a modifier, and other factors.

The lemma forms of words, which is the form chosen by convention as the canonical form of a word, is usually the most unmarked or basic case, which is typically the nominative, trigger, or absolutive case, whichever a language may have.