Definition:
A word that shows the relation of a noun or pronoun to some other word in a sentence. A postposition is similar in function to a preposition, but it follows rather than precedes the object.
The only common postposition in English is the word ago.
Together, prepositions and postpositions are called adpositions
Examples and Observations:
- "I can remember only a few of the strange and curious words now dead but living and spoken by the English people a thousand years ago."
(Carl Sandburg) - "Sixty years ago I knew everything; now I know nothing; education is a progressive discovery of our own ignorance."
(Will Durant) - "Ago in English must follow its complement.
(87a) John received a very generous offer a few minutes ago.
In contrast with notwithstanding, ago must piedpipe, and cannot strand.
(87b) *John received a very generous offer ago a few minutes.(88a) How long ago did John receive the offer?
(Peter W. Culicover, Syntactic Nuts: Hard Cases, Syntactic Theory, and Language Acquisition. Oxford Univ. Press, 1999)
(88b) *How long did John receive the offer ago?" - "Although ago is . . . usually said to be the only independent postposition of English, the formal use of hence with the meaning 'from now' (as in three weeks hence) seems to be used identically. Traces of postpositional constructions are found in expressions like the whole week through and all the year round."
(D.J. Allerton, "'Over the Hills and Far Away' or 'Far Away Over the Hills': English Place Adverb Phrases and Place Prepositional Phrases in Tandem." Adpositions: Pragmatic, Semantic and Syntactic Perspectives, ed. by Dennis Kurzon and Silvia Adler. John Benjamins, 2008) - "Though not usually so treated, the clitic -'s could be seen as a postposition in e.g. my friend's daughter, my friend in Washington's daughter."
(P.H. Matthews, The Concise Oxford Dictionary of Linguistics. Oxford Univ. Press, 2007) - "Many languages, such as English, express thematic roles by means of prepositions. Some languages, however, use postpositions (i.e., morphemes that express the same thematic roles but come after head nouns). Languages that use postpositions in this way include Korean and Japanese. . . .
"For those students who have prepositions or postpositions in their native language, English prepositions are still a source of difficulty, and they remain so even as students' levels of proficiency increase. One reason for this is the problem of polysemy. In learning a second language, students attempt to draw correspondences between their L1 [native language] prepositions and prepositions in the L2 [second language]. Perfect one-to-one correspondences would facilitate learning, but, given polysemy, finding these is virtually impossible."
(Ron Cowan, The Teacher's Grammar of English: A Course Book and Reference Guide. Cambridge Univ. Press, 2008)

