A preposition is a word that shows the relationship between a noun or a pronoun and another word (or words) in a sentence.

A word that shows the relationship between its object; the noun or pronoun following the preposition, and other words in a sentence.

The following examples that are in bold type are prepositions:

• The book on the table is a dictionary.
• The book next to the table is a dictionary.
• The book near the table is a dictionary.