preposition

Etymology 1

From Middle English preposicioun, from Old French preposicion, from Latin praepositio, praepositionem, from praepono (“to place before”). Compare French préposition. So called because it is placed before the word with which it is phrased, as in a bridge of iron, he comes from town, it is good for food, he escaped by running.

noun

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.
   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. Jun 1 2014, “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.
   […] he made a longe preposicion & oracion cōcernynge yͤ allegiaūce which he exortyd his lordes to owe 1811 [1516], Robert Fabyan, edited by Sir Henry Ellis, The New Chronicles of England and France, page 116

Etymology 2

pre- + position

verb

1. To place in a location before some other event occurs.
   It is important to preposition the material before turning on the machine.