What is the meaning of kick the bucket?

verb

• Pass from physical life and lose all bodily attributes and functions necessary to sustain life.
  • usage: "She died from cancer"; "The children perished in the fire"; "The patient went peacefully"; "The old guy kicked the bucket at the age of 102"
  • synonyms: die, decease, perish, go, exit, pass away, expire, pass, cash in one's chips, buy the farm, conk, give-up the ghost, drop dead, pop off, choke, croak, snuff it