A preposition is a word which precedes a noun (or a pronoun) to show the noun's (or the pronoun's) relationship to another word in a sentence. The word preposition means positioned before. A preposition almost always precedes a noun or a pronoun. across, against, along, around, at, before, behind, below, beneath, beside, between, beyond, by, down, during, except, for, from, in, into, like, near, of, off, up, upon, with and within are some examples of prepositions.