Onomatopoeic things sound like or suggest just what they mean: words like "cough," "bang," and "sizzle" are onomatopoeic.
One very obvious onomatopoeic example is animal sounds — we have words in English like bark, oink, and ribbit that mimic the sounds they're describing. Other examples of onomatopoeic words are hiccup, zipper, and splash. In Greek, onomatopoiia means "the making of a name or word," from onoma, "word or name," and poiein, "make."