What is the meaning of the word "street name"?

Definitions:

  1. an alternative name that a person chooses or is given copy to clipboard noun
    • They were better known by their street name than the name on their birth certificate. copy to clipboard
  2. slang for something (especially for an illegal drug) copy to clipboard noun
    • `smack' is a street name for heroin copy to clipboard
  3. the name of a brokerage firm in which stock is held on behalf of a customer copy to clipboard noun
    • all my stocks are held in street name copy to clipboard