1. (n.)billion a cardinal number represented by 1 followed by 9 zeroes; a thousand millions.
2. billion (in Great Britain) a cardinal number represented by 1 followed by 12 zeroes; a million millions.
3. billion any vaguely large number: I've told you a billion times.
4. (adj.)billion equal in number to a billion.
Etymology: (1680–90; < F)
Definition of 'Billion'
Princeton's WordNet
1. (noun)billion, one million million, 1000000000000 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
2. (noun)million, billion, trillion, zillion, jillion, gazillion a very large indefinite number (usually hyperbole) "there were millions of flies"
3. (adj)billion, one thousand million, 1000000000 the number that is represented as a one followed by 9 zeros
4. (adj)billion denoting a quantity consisting of one thousand million items or units in the United States
5. (adj)billion denoting a quantity consisting of one million million items or units in Great Britain
1. billion 1,000,000,000 more than three billion dollars; "How many?" "A billion."; billions of atoms
Definition of 'Billion'
Webster Dictionary
1. (noun)Billion according to the French and American method of numeration, a thousand millions, or 1,000,000,000; according to the English method, a million millions, or 1,000,000,000,000. See Numeration
Sense: often in the United Kingdom, the number 1,000,000,000,000; in the United States, and often in the United Kingdom, the number 1,000,000,000 a billion; several billion.
Definitions of Billion 
Afrikaans: biljoen, miljard
Arabic: بليون
Bulgarian: билион, ам. Милиард
Brazilian: bilhão
Czech: bilion; miliarda
German: die Billion; die Milliard
Danish: billion; milliard
Greek: δισεκατομμύριο, τρισεκατο
Spanish: billón; millardo (Estados
Estonian: biljon, miljard
Farsi: یک میلیارد
Finnish: miljardi
French: billion; (É.-U.) milliard
Hebrew: מִיליָארד
Hindi: अमेरिका में एक अरब
Croatian: milijarda
Hungarian: GB billió, US milliárd
Indonesian: bilyun, milyar
Icelandic: biljón (miljón miljónir);
Italian: bilione, miliardo
Japanese: 10億 (英国で時に兆)
Korean: (미국) 10억
Lithuanian: bilijonas, milijardas
Latvian: miljards: 109; Lielbritān
Malay: bilion
Dutch: biljoen
Norwegian: billion (en million milli
Polish: bilion, miliard
Persian: یک میلیارد
Portuguese: bilião
Romanian: miliard
Russian: триллион; миллиард
Slovak: bilión; miliarda
Slovenian: bilijon; (ZDA) milijarda
Serbian: milijarda
Swedish: biljon, miljard
Thai: ล้านล้าน (อังกฤษ); พันล้า
Turkish: milyar
Taiwanese: (數量)萬億(英舊用法)，十億(英美常用)
Ukrainian: більйон; мільярд
Urdu: ایک کھرب
Vietnamese: một nghìn tỉ (Anh, Đức), 
Chinese: （数量）万亿（英旧用法），十亿（英美常用）
