Adpositions are a class of words used to express spatial or temporal relations (in, under, towards, behind, ago, etc.) or mark various semantic roles (of, for).[1] The most common adpositions are prepositions (which precede their complement) and postpositions (which follow their complement).
An adposition typically combines with a noun phrase, this being called its complement, or sometimes object. English generally has prepositions rather than postpositions – words such as in, under and of precede their objects, such as in England, under the table, of Jane – although there are a few exceptions including ago and notwithstanding, as in "three days ago" and "financial limitations notwithstanding". Some languages that use a different word order have postpositions instead (like Turkic languages) or have both types (like Finnish). The phrase formed by an adposition together with its complement is called an adpositional phrase (or prepositional phrase, postpositional phrase, etc.). Such a phrase can function as an adjective or as an adverb.
A less common type of adposition is the circumposition, which consists of two parts that appear on each side of the complement. Other terms sometimes used for particular types of adposition include ambiposition, inposition and interposition. Some linguists use the word preposition in place of adposition regardless of the applicable word order.[2]