A bitbucket is a term used to refer to any form of computer data or information that has disappeared or been lost for reasons that are inexplicable. The bitbucket refers to the mysterious place where this information has gone. For example, if a user accidentally loses an important text file on his computer, someone might say to him, "I guess it has gone to the bitbucket."
This term is also used when performing computer-related bit shift operations. When a bit shift is performed, any bits of information that are deleted by this process are said to have "fallen in the bitbucket."