What is the meaning of the word "shakedown"?

Definitions:

  1. a very thorough search of a person or a place copy to clipboard noun
    • a shakedown by the police uncovered the drugs copy to clipboard
  2. initial adjustments to improve the functioning or the efficiency and to bring to a more satisfactory state copy to clipboard noun
    • the new industry's economic shakedown copy to clipboard
  3. intended to test a new system under operating conditions and to familiarize the operators with the system copy to clipboard adjective
    • a shakedown cruise copy to clipboard