The prepositional case is the grammatically required derivative of a word, primarily nouns and pronouns, when it is part of a prepositional phrase. A preposition is a word relating one noun to other words, such as by direction, location or position. With the exception of pronouns, which change form based on grammar in many languages, it is uncommon. The Slavic languages, such as Russian and Czech, along with Spanish and Portuguese are examples of languages which use the prepositional case.
Examples of prepositions include the words above, through, and in. A preposition is always paired with a noun object. The following is a sentence with a prepositional phrase: “He sent a message to her.” While the word “she” is the subjective case for a singular female, a different form of the pronoun — her — is used because it is the object of the preposition “to.” Although there is some disagreement on definition, the prepositional case is also sometimes called the locative case.
Theorists of linguistics and others who study language presume that this prepositional pronoun change common to many languages is to make the relation between people more definite. Some languages having no prepositional case may rely entirely on the placement of nouns to establish their relation. For the above sentence, the word order “he-message-she” might be sufficiently understood without resorting to an entirely different case for the words. In written Portuguese, some pronouns do not change, but are new words derived by combining and contracting the pronoun with the preposition.
The Russian and Polish languages employ a strict prepositional case for a few select prepositions, namely for the equivalent of the English words on, in, near, and about. Any noun to follow these words as the object of the preposition must be changed with the attachment of their respectively correct suffix. Adjectives that describe this noun must also be changed to reflect this grammatical case.
Except for pronouns, English does not use different words to distinguish whether a noun is subjective or objective. Other languages, such as German and Latin, do change the form of their nouns slightly. Very few languages go further with prepositional cases to separate nouns used as direct objects, indirect objects or objects of a preposition. Some languages may not have a separate case, but might require additional rules of grammar. Spanish, for example, requires a second preposition — equivalent to “of” — when the object noun is a word representing a human being.