Definition of "preposition"

preposition¹

/ˌpɹɛpəˈzɪʃən/

noun
plural prepositions
1. (grammar, strict sense) Any of a class of non-inflecting words typically employed to connect a following noun or a pronoun, in an adjectival or adverbial sense, with some other word: a particle used with a noun or pronoun (in English always in the objective case) to make a phrase limiting some other word.
  Quotations
  And in (121) below, we see that when a wh-NP is used as the Object of a Preposition, the whole Prepositional Phrase can undergo WH MOVEMENT: (121) (a) [To whom] can I send this letter —? (121) (b) [About what] are they quarrelling —? (121) (c) [In which book] did you read about it —?
  1988, Andrew Radford, chapter 9, in Transformational grammar: a first course, Cambridge, UK: Cambridge University Press, page 495
  I love this girl. “On which I can get my hands” — even in her darkest moment, she cannot bring herself to end a sentence with a preposition.
  2014 June 1, “Net Neutrality”, in Last Week Tonight with John Oliver, season 1, episode 5, John Oliver (actor), via HBO
2. (grammar, broad sense) An adposition.
3. (obsolete) A proposition; an exposition; a discourse.
  Quotations
  […] he made a longe preposicion & oracion cōcernynge yͤ allegiaūce which he exortyd his lordes to owe
  1811 , Robert Fabyan, edited by Sir Henry Ellis, The New Chronicles of England and France‎, page 116

preposition²

/ˈpɹiːpəˌzɪʃən/

verb
third-person singular simple present prepositions, present participle prepositioning, simple past and past participle prepositioned
1. To place in a location before some other event occurs.