"Kick the bucket" is a colloquial, often darkly humorous way of saying someone has died. It is informal and would be inappropriate in sensitive contexts. It can be used figuratively of machines or objects that have stopped working: "My old laptop finally kicked the bucket."
The most credible etymology comes from the slaughter of pigs. In the 16th and 17th centuries, the Old French word buquet (and Middle English bucket) could refer to a trebuchet — a balance beam or wooden frame. Pigs to be slaughtered were hung from such a frame by their heels. As the animal died, it would thrash and kick — kicking the "bucket." An 1823 dictionary of slang, A Classical Dictionary of the Vulgar Tongue by Francis Grose, contains a definition consistent with this origin.
A second theory holds that the phrase refers to suicide by hanging: a person would stand on a bucket, tie a noose, and kick the bucket away. While this image is vivid and frequently cited, historians note that this is not strongly supported by early texts, and the slaughterhouse theory has better documentary evidence.
The phrase appears in print by the late 18th century. By the 19th century it was established slang in Britain and America. The 1823 slang dictionary referenced above notes "kick the bucket" meaning to die, with the pig-slaughtering context as the explanation.
Most languages have colourful euphemisms for death. In French: "casser sa pipe" (break one's pipe). In German: "den Löffel abgeben" (hand in the spoon). In Spanish: "estirar la pata" (stretch the leg). Dark humour around death is a universal human trait.
It is informal and darkly humorous — appropriate in casual conversation but not in sensitive or formal situations such as obituaries, condolences, or professional contexts.
The phrase 'bucket list' — a list of things to do before you die — is a direct play on 'kick the bucket.' The term was popularised by the 2007 film The Bucket List starring Jack Nicholson and Morgan Freeman.