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.]
1. (Arith.) A cipher; nothing; naught.
2. The point from which the graduation of a scale, as of a
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
3. Fig.: The lowest point; the point of exhaustion; as, his
patience had nearly reached zero.
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.