complement

complement: see immunity.

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complement

In physiology, a complex system of at least 20 proteins (complement components) in normal blood serum. The binding of one component to an antigen-antibody complex begins a chemical chain reaction important in many immunological processes, including breakdown of foreign and infected cells, ingestion of foreign particles and cell debris, and inflammation of surrounding tissue. Complement components and antibodies are the substances in human serum responsible for killing bacteria.

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The number derived by subtracting a number from a base number. For example, the tens complement of 8 is 2. In set theory, complement refers to all the objects in one set that are not in another set.

Complements are used in digital circuits, because it's faster to subtract by adding complements than by performing true subtraction. The binary complement of a number is created by reversing all bits and adding 1. The carry from the high-order position is eliminated. The following example subtracts 5 from 8.

     Decimal    Binary    Complement
      8          1000      1000
     -5         -0101     +1011
     __         _____     _____
      3          0011      0011

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(logic)

complement - The other value or values in the set of possible values. See logical complement, bitwise complement, set complement.