1. 1. A member of the left-wing majority group of the Russian Social Democratic Workers' Party that adopted Lenin's theses on party organization in 1903.
   2. A member of the Russian Social Democratic Workers' Party that seized power in that country in November 1917.
   3. A member of a Marxist-Leninist party or a supporter of one; a Communist.
2. often bolshevik An extreme radical: a literary bolshevik.

Word History: The word Bolshevik, an emotionally charged term in English, is derived from an ordinary word in Russian, bol'she, "bigger, more," the comparative form of bol'shoĭ, "big." The plural form Bol'sheviki was the name given to the majority faction at the Second Congress of the Russian Social Democratic Workers' Party in 1903 (the term is first recorded in English in 1907). The smaller faction was known as Men'sheviki, from men'she, "less, smaller," the comparative of malyĭ, "little, few." The Bol'sheviki, who sided with Lenin in the split that followed the Congress, subsequently became the Russian Communist Party. In 1952 the word Bol'shevik was dropped as an official term in the Soviet Union, but it had long since passed into other languages, including English.