ThE ZERo

ze·ro (zîr'ō, zē'rō) n., pl. -ros or -roes.

The numerical symbol 0; a cipher.
Mathematics.
The identity element for addition.
A cardinal number indicating the absence of any or all units under consideration.
An ordinal number indicating an initial point or origin.
An argument at which the value of a function vanishes.
The temperature indicated by the numeral 0 on a thermometer.
A sight setting that enables a firearm to shoot on target.
Informal. One having no influence or importance; a nonentity: a manager who was a total zero.
The lowest point: His prospects were approaching zero.
A zero-coupon bond.
Informal. Nothing; nil: Today I accomplished zero.
adj.
Of, relating to, or being zero.

Having no measurable or otherwise determinable value.
Informal. Absent, inoperative, or irrelevant in specified circumstances: “The town has . . . practically no opportunities for amusement, zero culture” (Robert M. Adams).
Meteorology.
Designating a ceiling not more than 16 meters (52 feet) high.
Limited in horizontal visibility to no more than 55 meters (180 feet).
Linguistics. Of or relating to a morpheme that is expected by an established, regular paradigm but has no spoken or written form. Moose has a zero plural; that is, its plural is moose.
tr.v., -roed, -ro·ing, -roes.
To adjust (an instrument or a device) to zero value.
phrasal verbs:
zero in

To aim or concentrate firepower on an exact target location.
To adjust the aim or sight of by repeated firings.
To converge intently; close in: The children zeroed in on the display of toys in the store window.
zero out
To eliminate (a budget or budget item) by cutting off funding.
To reduce to zero.
[Italian, from alteration of Medieval Latin zephirum, from Arabic ṣifr, nothing, cipher.]


Zero
In mathematics, the concept zero is used in two ways: as a number and as a value of a variable. The positional system of number notation, developed first by the Babylonians (about 500 b.c.) with the base 60, and a millennium later by the Hindus and the Chinese with the base 10, required for greater clarity a special marker of the empty, nonoccupied position.
The zero as a number, however, is a new concept, introduced by the Hindus and Chinese about the same time (6th century). Brahmagupta (born a.d. 598) remarked that the number 0 has special properties: a ± 0 = a, and a · 0 = 0, where a may be any number (integer).
In a modern way, zero can be called the identity element of the infinite Abelian additive group of integers. If in an integral domain a product is equal to zero, then at least one factor of the product is zero. In the second concept zero is the value of a variable for which a function is equal to zero.

zero also zero in
noun
A totally insignificant person: cipher, nebbish, nobody, nonentity, nothing. Informal pip-squeak. Slang shrimp, zilch. See important/unimportant.
No thing; not anything: nil, nothing, null. Slang nix, zilch. Archaic aught. See absence.
phrasal verb - zero in
To move (a weapon or blow, for example) in the direction of someone or something: aim, cast, direct, head, level, point, set1, train, turn. Military lay1. See seek/avoid.
zero, that number which, when added to any number, leaves the latter unchanged; its symbol is 0. The introduction of zero into the decimal system was the most significant achievement in the development of a number system in which calculation with large numbers was feasible. Without it, modern astronomy, physics, and chemistry would have been unthinkable as we know them. The lack of such a symbol was one of the serious drawbacks of Greek mathematics. Its existence in the West is probably due to the Arabs, who, having obtained it from the Hindus, passed it on to European mathematicians in the latter part of the Middle Ages. The Maya of Central America and probably the Babylonians also invented zero. With the extension of the number system to negative as well as positive numbers, zero became the name for that position on the scale of integers between −1 and +1. It is used in this sense in speaking of zero degrees on the Fahrenheit and Celsius temperature scales; “absolute zero” is a term used by physicists and chemists to indicate the theoretically lowest possible temperature—a use reminiscent of zero as a symbol for nothing. Unlike other numbers, zero has certain special properties in connection with the four fundamental operations. By definition zero added to or subtracted from any number leaves the number unchanged. Any number multiplied by zero gives zero. Zero multiplied by or divided by any number (other than zero) is still zero. But division by zero is undefined; i.e., there is no number that is the value of a number divided by zero.
zero (complex analysis)
In complex analysis, a zero of a holomorphic function f is a complex number a such that f(a) = 0.
Multiplicity of a zero
A complex number a is a simple zero of f, or a zero of multiplicity 1 of f, if f can be written as
where g is a holomorphic function g such that g(a) is not zero.
Generally, the multiplicity of the zero of f at a is the positive integer n for which there is a holomorphic function g such that
Existence of zeros
The fundamental theorem of algebra says that every nonconstant polynomial with complex coefficients has at least one zero in the complex plane. This is in contrast to the situation with real zeros: some polynomial functions with real coefficients have no real zeros (but since real numbers are complex numbers, they still have complex zeros). An example is f(x) = x2 + 1.
Properties
An important property of the set of zeros of a holomorphic function (that is not identically zero) is that the zeros are isolated. In other words, for any zero of a holomorphic function , there is a small disc around the zero which contains no other zeros. There are also some theorems in complex analysis which show the connections between the zeros of a holomorphic (or meromorphic) function and other properties of the function. In particular Jensen's formula and Weierstrass factorization theorem are results for complex functions which have no counterpart for functions of a real variable.

ThE ENd.