Definitions of street name:

• noun:   the name of a street
• noun:   the name of a brokerage firm in which stock is held on behalf of a customer

  Example: "All my stocks are held in street name"

• noun:   a slang term for something (especially for an illegal drug)

  Example: "`smack' is a street name for heroin"

• noun:   an alternative name that a person chooses or is given (especially in inner city neighborhoods)

  Example: "Her street name is Bonbon"