Billion (noun)

1. The number equivalent to 1,000 million (1,000,000,000).
2. A very large amount or number.

Origin:

Late 16c., from french billion, billion, from mille "thousand" + billion "billion," from bi- "two" + billion "billion", from latin mille "thousand" (see million). billion in the modern sense (1,000 million) was first recorded 1795.

Examples:

1. The company has a billion dollars in revenue.
2. He's worth a billion dollars.
3. The population of the country is a billion.
4. The number of stars in the galaxy is estimated to be in the billions.
5. The cost of the project is in the billions of dollars.