An onomatopoeia is a word that imitates or suggests the source of the sound that it makes. The document provides examples of onomatopoeic words like splash, boom, honk, moo, neigh, clap, waah, quack, shhh, ruuff, and meow that mimic the sounds made by things like water, thunder, cars, cows, horses, babies, ducks, kids, dogs, and cats. It includes a poem and exercises to help identify onomatopoeic words.