What is a preposition? A preposition is a word governing, and usually preceding, a noun or pronoun and expressing a relation to another word or element in the clause, as in “the man on the platform,” “she arrived after dinner,” “what did you do it for ?” In Irish, prepositions more often FOLLOW another word or element, such as "Tá airgead agam" There is money at me = I have money. "Tá athas orm" Happiness is on me = I am happy.