Onomatopoeic words are words which resemble the sound they refer to; for example words to describe animal sounds generally imitate the sounds themselves. These words, also known as imitative and echoic words, are used by poets, comic-strip writers and authors of children's books among others. Here is a partial list of onomatopoeic words.
Perhaps more interesting is that onomatopoeic words exist in all languages. The most entertaining examples are the words used to describe the sounds that animals make. For example, in English, horses neigh or whinny, however in Norwegian they knegger and in Portuguese they relincha. In English the rooster says "cock a doodle do," and in Chinese "gou gou," and in Thai, "ake-e-ake-ake." For more of these, visit Sounds of the World's Animals.