billion
noun
the number that is represented as a one followed by 12 zeros; in the United Kingdom the usage followed in the United States is frequently seen
a very large indefinite number (usually hyperbole)
“there were millions of flies”
the number that is represented as a one followed by 9 zeros
adjective
denoting a quantity consisting of one thousand million items or units in the United States
denoting a quantity consisting of one million million items or units in Great Britain
Source: WordNet 3.1, Princeton University
