Definition - A word, such as above or about, that shows the relationship between a noun (or a pronoun) and another word.

Example -
In the sentence He sat above them, the preposition above shows the relationship between he and them.

Etymology -
The word derives from the Latin præpositionem, a putting before (from the Latin præ, before + ponere, place). The Latin grammatical term was coined as a loan translation of the Greek grammatical term prothesis, a setting before.

Oxford English Dictionary -
Its first citation is from approximately 1000 CE (from Aelfric's Grammar): "Praepositio est pars orationis indeclinabilis…."
(Ælfric Gram. xlvii. (Z.), 267 )

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