to utter or imitate the soft, murmuring sound characteristic of doves.
to murmur or talk fondly or amorously.
(intr) (of doves, pigeons, etc) to make a characteristic soft throaty call
(tr) to speak in a soft murmur
(intr) to murmur lovingly (esp in the phrase bill and coo )
First recorded in 1660–70; imitative
First recorded in 1910–15; origin uncertain
A coo is the low, sweet sound that a bird makes, especially a dove or pigeon. If a dove builds a nest outside your open window, you'll be able to hear its coos every morning. There is a small, gray pigeon that's called a mourning dove because its coo is so sad sounding. When you hear a bird making this distinctive sound, you can also say that it coos — and if a person murmurs in a low, soft voice, you can say that she coos too. The word coo has been used since at least the late 1600s, and its origin is probably imitative, the word sounding very much like the sound it describes.
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
As the family is photographed, several Aces members come in and pause for a brief hug and coo before ducking quickly out of frame.
From Los Angeles Times • May 13, 2026
If at all possible, you should live in a place where you don't have to constantly be looking over your shoulder in fear while you coo at the baby.
From Science Daily • Mar. 18, 2024
They coo and fuss over the infant, swap feeding and nappy-changing duties, and take turns to stay with him so one of them can get some sleep.
From BBC • Oct. 2, 2023
"My princess," she would coo to me, brushing my hair away from my tears.
From Salon • May 13, 2023
Millions of birds were roosting in the trees—fat gray-and-white pigeons, except they didn’t coo like regular pigeons.
From "The Sea of Monsters" by Rick Riordan
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
