To make the soft murmuring sound of a dove or pigeon. To speak in a gentle, soothing manner.
Middle English 'couen', imitative of the sound made by doves and pigeons. The word is onomatopoeic, directly mimicking the natural sound it describes, with similar forms found across many languages.
The word 'coo' is one of the purest examples of onomatopoeia in English, and babies often make cooing sounds before they can form words, suggesting this might be one of humanity's most instinctive vocalizations. Interestingly, the gentle nature of dove calls has made 'coo' synonymous with tender, loving speech.
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