Warning: Don't try spelling this at home.
Onomatopoeia - as poetry lovers may recall from 9th grade English---is the use of words that have no meaning in themselves, but imitate sounds we hear in the world around us.
Oink is onomatopoetic. Just like moo, meow, ribbit, and cluck.
So is woooooosh, to convey the sound of wave coming in, or Wham! Pow! Biff, to convey the vigor of fight between superheroes.
Obviously, onomatopoeia is not a prime strategy for the academic paper. It's hard to imagine (unless you are actually writing about onomatopoeia) how sound-like words would be appropriate at all in the scholarly context.
But it's a nifty word to know. And it does remind even scholarly writers how important the sound of words can be. Intuitively, for instance, when writing about war or other violent topics, writers will rely on words with Germanic roots more heavily than on Latinate ones, since the former tend to be choppier, more turbulent-sounding.
If you've become satisfied with your ability to build an argument; to develop clean sentences, coherent paragraphs, and logical transitions - then maybe it's time to start thinking about the sound of your writing. Try reading your next rough draft aloud before you revise. Listen for whether the rhythm of the language matches the flow of the argument. Consider whether shorter words might better serve you if you're trying to convey an awkward concept, or if Latinate words might work better where your topic is romantic poetry.