Preposition and Postposition - Definitional Issues

Definitional Issues

There are many different types of adpositions, and some adpositions can also be classified as verbs, nouns, or adjectives. It is thus impossible to provide an absolute definition that picks out all and only the adpositions in every language. The following features, however, are often required of adpositions.

• An adposition prototypically combines syntactically with exactly one complement phrase, most often a noun phrase (or, in a different analysis, a determiner phrase). (In some analyses, an adposition need have no complement. See below.) In English, this is generally a noun (or something functioning as a noun, e.g., a gerund), called the object of the preposition, together with its attendant modifiers.
• An adposition establishes the grammatical relationship that links its complement to another word or phrase in the context. In English, it may also establish a semantic relationship, which may be spatial (in, on, under, ...), temporal (after, during, ...), or logical (via, ...) in nature. The World Atlas of Language Structures treats a word as an adposition if it takes a noun phrase as complement and indicates the grammatical or semantic relationship of that phrase to the verb in the containing clause.
• An adposition determines certain grammatical properties of its complement (e.g. its case). In English, the objects of prepositions are always in the objective case (where such case is available: i.e. pronouns). In Koine Greek, certain prepositions always take their objects in a certain case (e.g., ἐν always takes its object in the dative), and other prepositions may take their object in one of several cases, depending on the meaning of the preposition (e.g., διά takes its object in the genitive or in the accusative, depending on the meaning).
• Adpositions are non-inflecting (or "invariant"); i.e., they do not have paradigms of forms (for different tenses, cases, genders, etc.) in the same way as verbs, adjectives, and nouns in the same language. There are exceptions, though, for example in Celtic languages (see Inflected preposition).