The Free On-line Dictionary of Computing (19 January 2023):

overflow bit
overflow flag

    A processor flag bit set by the ALU to
   indicate overflow.

   (2008-05-30)


The Jargon File (version 4.4.7, 29 Dec 2003):

overflow bit
 n.

    1. [techspeak] A flag on some processors indicating an attempt to
    calculate a result too large for a register to hold.

    2. More generally, an indication of any kind of capacity overload
    condition. “Well, the Ada description was baroque all right, but I could
    hack it OK until they got to the exception handling ... that set my
    overflow bit.”

    3. The hypothetical bit that will be set if a hacker doesn't get to make a
    trip to the Room of Porcelain Fixtures: “I'd better process an internal
    interrupt before the overflow bit gets set.”

    [73-07-24]

    Crunchly and the overflow bit.