wheel bit

n. 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.

