The Collaborative International Dictionary of English v.0.48:

Null \Null\, n.
   1. Something that has no force or meaning.
      [1913 Webster]

   2. That which has no value; a cipher; zero. --Bacon.
      [1913 Webster]

   Null method (Physics.), a zero method. See under Zero.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Zero \Ze"ro\, n.; pl. Zerosor Zeroes. [F. z['e]ro, from Ar.
   [,c]afrun, [,c]ifrun, empty, a cipher. Cf. Cipher.]
   [1913 Webster]
   1. (Arith.) A cipher; nothing; naught.
      [1913 Webster]

   2. The point from which the graduation of a scale, as of a
      thermometer, commences.
      [1913 Webster]

   Note: Zero in the Centigrade, or Celsius thermometer, and in
         the R['e]aumur thermometer, is at the point at which
         water congeals. The zero of the Fahrenheit thermometer
         is fixed at the point at which the mercury stands when
         immersed in a mixture of snow and common salt. In
         Wedgwood's pyrometer, the zero corresponds with
         1077[deg] on the Fahrenheit scale. See Illust. of
         Thermometer.
         [1913 Webster]

   3. Fig.: The lowest point; the point of exhaustion; as, his
      patience had nearly reached zero.
      [1913 Webster]

   Absolute zero. See under Absolute.

   Zero method (Physics), a method of comparing, or measuring,
      forces, electric currents, etc., by so opposing them that
      the pointer of an indicating apparatus, or the needle of a
      galvanometer, remains at, or is brought to, zero, as
      contrasted with methods in which the deflection is
      observed directly; -- called also null method.

   Zero point, the point indicating zero, or the commencement
      of a scale or reckoning.
      [1913 Webster]
      [1913 Webster]