1. The number that is represented as a one followed by 9 zeros
   "The company's revenue exceeded a billion dollars";
   - one thousand million, 1000000000
    
2. [informal] A very large indefinite number (usually hyperbole)
   "there were billions of flies";
   - million [informal], trillion [informal], zillion [informal], jillion [N. Amer, informal], gazillion [informal], bazillion [N. Amer, informal], bajillion [informal], squillion [informal]
    
3. [Brit, archaic] (UK historical) one million million (10¹²)
   "In modern usage a billion is 1,000,000,000, while in the UK was traditionally 1,000,000,000,000"

1. Denoting a quantity consisting of one thousand million items or units
    
2. [Brit, archaic] Denoting a quantity consisting of one million million items or units

Derived forms: billions

See also: cardinal

Type of: large indefinite amount, large indefinite quantity, large integer

Encyclopedia: Billion