1. [mid-19C] a short iron crowbar, used by criminals.
2. [mid–late 19C] (UK Und.) stolen metal.
3. [mid-19C+] (orig. US, also bill, billie, billy stick) a policeman’s wooden club (orig. untanned cowhide, covered in wool).
4. [mid-19C+] a form of blackjack, usu. ‘loaded’ with lead.
5. [1960s] (US) a police officer; the police as a group.
6. [2000s] (US prison) a white man.
[1960s] (US) a policeman.
[mid-19C] trading in old (poss. stolen) metal; thus billy-hunter, billy-prigger, a trader in such metal.
[1960s] a policeman.