Brook/brʊk/ Definition 1 of 2Pro Tip 1/3Natural Imagery Brook as a noun often evokes peaceful, natural scenes in literature and poetry. The gentle brook provided a serene soundtrack to our picnic. Pro Tip 2/3Size Matters A brook is smaller than a river. Use it to describe tiny streams, not large bodies of water. Children love to play by the shallow brook. Pro Tip 3/3Descriptive Word 'Babbling' is often used with brook to describe the sound of the water flowing over rocks. We fell asleep listening to the babbling brook.