Definition of "whizzer"

whizzer

noun
plural whizzers
1. A set of horizontal blades used to separate mineral particles.
2. A device used in milling to dry wheat, etc. by rapid spinning.
3. (UK, slang) A pickpocket.
  Quotations
  In order better to appreciate the use of argot among thieves, a visit to a few public bars of the third-class public houses of Kennington or in the immediate vicinity of the Elephant and Castle would prove of great value, as hoisters, whizzers, tea-leaves, con-heads, broadsmen and brass nobs […]
  1931, The Police Journal, volume 4, page 504
  It is doubtful if the Victorian Londoner needed any warning, for the artful mobsmen, toolers, whizzers and dippers, together with their stickman accomplices, were everywhere in the crowds, in the underground, on railway trains […]
  1976, Michael Harrison, Beyond Baker Street: A Sherlockian Anthology, page 117
  They were whizzers (pickpockets) but they would also take part in burglaries.
  1981, East End Underworld, page 146
  He knew the whizzers – those innocent-looking men who crowd into omnibuses and rob the poor of their bitterly won earnings […]
  2012, Edgar Wallace, The Flying Squad
4. (historical) Synonym of whizgig (“spinning toy”)