Prepositions which are formed in imitation of unspoken sounds , words or sounds are called imitative or phonetic prepositions. For example : thunder: thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder, thunder , thunder , thunder ,