preposition

 /ˌprep.əˈzɪʃ.ən/

in grammar, a word that is used before a noun, a noun phrase, or a pronoun, connecting it to another word:

In the sentences "We jumped in the lake", and "She drove slowly down the track", "in" and "down" are prepositions.

Some prepositions consist of more than one word, such as 'out of'.