wheel bitn. A privilege bit that allows the possessor to perform some restricted operation on a timesharing system, such as read or write any file on the system regardless of protections, change or look at any address in the running monitor, crash or reload the system, and kill or create jobs and user accounts. The term was invented on the TENEX operating system, and carried over to TOPS-20, XEROX-IFS, and others. The state of being in a privileged logon is sometimes called `wheel mode'. This term entered the Unix culture from TWENEX in the mid-1980s and has been gaining popularity there (esp. at university sites). See also root.