Definition of moo in US English:


verbmooing, moos, mooed

[no object]
  • Make the characteristic deep vocal sound of a cow.

    • ‘I reached out to stick a finger into the pail when the cow mooed again.’
    • ‘Disturbed by Lewis's examination of her newborn, the heifer mooed unhappily.’
    • ‘We drove down a winding country road surrounded by large vegetable gardens in various stages of harvest, cow pastures with lots of passive cows mooing softly and small rural homes.’
    • ‘Adding to the mesmerizing murmur of the flowing water, the sounds of birds singing and cows mooing left one feeling totally at peace.’
    • ‘It was sleeping peacefully, mooing faintly and twitching its hooves.’
    • ‘Children were running everywhere, dogs were barking and cows were mooing.’
    • ‘Cattle and sheep started to roam languidly towards the hill slopes where they grazed, mooing and baaing.’
    • ‘She mooed loudly as though in shock, and ran in the opposite direction.’
    • ‘Quietly waiting, chewing their cuds, occasionally mooing, they look in from outside their barn doors at the plentiful picnic refreshments prepared for the human beings.’
    • ‘The rains began to pour down in heavy pelts, in huge droplets, the cows mooing a nervous call loud over the plateau.’
    • ‘Several of the bulls started bellowing and the cows mooing.’

nounPlural moos

  • The characteristic deep vocal sound of a cow.

    • ‘And how many times does a cow say moo in it's lifetime?’
    • ‘She got some that had cows and said moo on them.’
    • ‘Where life still revolves around the temple, and cows have homes where they are guaranteed dinner - if they stand outside and moo.’
    • ‘She withdrew her hand, and nearly jumped as the cow let out a soft, gentle moo.’
    • ‘George can only quack, oink, moo, and meow.’


Mid 16th century: imitative.