Onomatopoeia

on•o•mat•o•poe•ia /ˌɑnəˌmætəˈpiə, -ˌmɑtə-/ n. 

[uncountable]

1. the formation of a word, as cuckoo or boom, by imitating the sound made by or associated with the thing the noun refers to:In English, onomatopoeia is found in words like tweet, zap, flick,and hiss.
2. the use of such imitative words, as in poetry. (WR)