OXFORD DICTIONARY
Preposition, n. Gram. a word governing (and usu. preceding) a noun or pronoun and expressing a relation to another word or element, as in: 'the man on the platform', 'came after dinner', 'what did you do it for?'.
prepositional adj. prepositionally adv.
ME f. L praepositio f. praeponere praeposit- (as PRAE-, ponere place)
THESAURUS
Preposition
adjectival, adjective, adverb, adverbial, adversative conjunction, attributive, conjunction, conjunctive adverb, coordinating conjunction, copulative, copulative conjunction, correlative conjunction, disjunctive, disjunctive conjunction, exclamatory noun, form class, form word, function class, gerundive, interjection, part of speech, participle, particle, past participle, perfect participle, present participle, subordinating conjunction, verbal adjective