Merriam-Webster says:

1:  the naming of a thing or action by a vocal imitation of the sound associated with it (as buzz, hiss)

2:  the use of words whose sound suggests the sense says:
1.    the formation of a word, as cuckoo, meow, honk, or boom, by imitation of a sound made by or associated with its referent.
2.   a word so formed.
3.   the use of imitative and naturally suggestive words for rhetorical, dramatic, or poetic effect.
Like that.