Coo/kuː/ Definition 1 of 3Pro Tip 1/3Natural Sounds Used to describe the natural sounds made by birds, especially for doves and pigeons. The park was quiet except for the gentle coo of pigeons. Pro Tip 2/3Peaceful Imagery 'Coo' often evokes a sense of calm and tranquility in nature scenes. The cooing doves added to the serene atmosphere of the garden. Pro Tip 3/3Onomatopoeia The word 'coo' mimics the sound itself, making it an onomatopoeic term. I mimicked the coo of the birds to attract them closer.