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

high bit
 n.

    [from high-order bit]

    1. The most significant bit in a byte.

    2. [common] By extension, the most significant part of something other than
    a data byte: ?Spare me the whole saga, just give me the high bit.? See
    also meta bit, dread high-bit disease, and compare the mainstream slang
    bottom line.


The Free On-line Dictionary of Computing (30 December 2018):

high bit

   (Or "high-order bit") The most significant bit in a byte.

   See also meta bit, hobbit, dread high bit disease.

   [Jargon File]

   (2012-08-31)