UNO
n. uncountablen. a popular card game where players try to be the first to get rid of all their cards. You have to match cards by color or number and shout the name of the game when you have only one card left.
n. a proprietary American card game played with a specially printed deck. Players race to empty their hands by matching the top card of the discard pile by color, number, or symbol.
We played a long game of Uno after dinner.
The children spent the rainy afternoon playing Uno, arguing over who had to draw four cards.
While the basic rules of Uno are simple enough for children, many families develop their own house rules regarding how 'Draw Two' and 'Wild' cards can be stacked during play.
Usually treated as a proper noun and capitalized; functions as an uncountable noun when referring to the game itself.