preposition

noun

1. (strict-sense)Any of a class of non-inflecting words and multiword terms 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.

   “322. The parts of speech which are neither declined nor conjugated, are called by the general name of particles. 323. They are adverbs, prepositions, conjunctions, and interjections.”

   “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 —?”

   “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.”

2. (broadly)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”

verb

1. (alt-of, alternative, proscribed, sometimes)Alternative spelling of pre-position.

   “It is important to preposition the material before turning on the machine.”