Basij: A volunteer militia force in Iran that the government calls out to quell street protests and other disturbances. The Basij also function as a conservative Islamist "morality police," enforcing modesty of dress and behavior among their fellow citizens.
The actual number of Basij members is unknown - estimates range between 400,000 and 20 million (cited by Ayatollah Khomeini as the ideal number). Most are young men from economically disadvantaged regions, although there is also a women's division called the Basiji al-Zahra.
The Basij originated as a civilian resistance force during the Iran/Iraq War of 1980-88. Members were used as cannon-fodder in that grueling conflict; some were sent on suicide missions to walk across minefields in order to clear them in front of the regular Iranian troops.
More recently, the Basij have been deployed to beat protesters when they take to the streets, as in the student protests of 1999 and 2003. Reportedly, some Basiji even threw students at Tehran University from their dorm-room windows to their deaths in quelling those protests.
Although they take orders from the Iranian Revolutionary Guards, the Basij are not technically a government force, providing the ayatollahs and the president with a bit of distance from and "plausible deniability" for their heavy-handed tactics.
The name "Basij" comes from the Farsi phrase Basij-e Mostaz'afin, meaning "Mobilization of the Oppressed."
"Plain-clothes members of the Basij militia attacked protesters in the aftermath of the disputed 2009 presidential election in Iran, whipping people with chains and beating them with sticks."