Meaning

noun a function word that combines with a noun or pronoun or noun phrase to form a prepositional phrase that can have an adverbial or adjectival relation to some other word

noun (linguistics) the placing of one linguistic element before another (as placing a modifier before the word it modifies in a sentence or placing an affix before the base to which it is attached)

originFrom Middle English preposicioun, from Old French preposicion, from Latin praepositio, praepositionem, from praepono (“to place before”), equivalent to pre- + position. 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.

Etymology from Wiktionary, CC BY-SA 3.0