Which term is defined as words that imitate sound and create an auditory effect in poetry?

Onomatopoeia is the term that refers to words that imitate sounds, creating an auditory effect that enhances the reader's experience in poetry and prose. This device allows the reader to hear the sounds associated with the actions or objects described, making the imagery more vivid and engaging.

In contrast, the other options focus on different aspects of sound in language. Alliteration involves the repetition of initial consonant sounds in closely positioned words, which can create rhythm and musicality but does not specifically imitate sounds. Consonance refers to the repetition of consonant sounds within or at the end of words in close proximity, also adding to the sound quality but not directly imitating sounds. Assonance involves the repetition of vowel sounds within nearby words, contributing to the flow and musicality but, like the others, does not imitate sounds directly. Thus, onomatopoeia stands out as the only term that specifically emphasizes the imitation of sound itself.