Definitions for "Sign Bit"
The most significant binary digit, or bit, of a signed binary number. If set to a logic 1, this bit represents a negative quantity.
A single bit, usually the most significant bit in a word, which is used to designate the algebraic sign of the information contained in the remainder of the word.
The most significant (leftmost) bit of a number field, usually set to 1 if the number is negative. When an 8-bit value is added to a 16-bit value using signed arithmetic, the microprocessor propagates the sign bit through the high order half of the 16-bit register holding the 8-bit value in a process called sign extension or sign propagation.