Zero–in–on

the figure or symbol 0, which in the arabic notation for numbers stands for the absence of quant-ty; cipher.
the origin of any kind of measurement; line or point from which all divisions of a scale, as a thermometer, are measured in either a positive or a negative direction.
a mathematical value intermediate between positive and negative values.
naught; nothing.
the lowest point or degree.
linguistics. the absence of a linguistic element, as a phoneme or morpheme, in a position in which one previously existed or might by -n-logy be expected to exist, often represented by the symbol 0̷:
inflectional endings were reduced to zero. the alternant of the plural morpheme in “sheep” is zero.
ordnance. a sight setting for both elevation and windage on any particular range causing a projectile to strike the center of the target on a normal day, under favorable light conditions, with no wind blowing.
mathematics.

the ident-ty element of a group in which the operation is addition.
(of a function, especially of a function of a complex variable) a point at which a given function, usually a function of a complex variable, has the value zero; a root.

(initial capital letter) a single-engine j-panese fighter plane used in world war ii.
to adjust (an instrument or apparatus) to a zero point or to an arbitrary reading from which all other readings are to be measured.
to reduce to zero.
slang. to kill (a congressional bill, appropriation, etc.):
the proposed tax increase has been zeroed for the time being.
amounting to zero:
a zero score.
having no measurable quant-ty or magnitude; not any:
zero economic growth.
linguistics. noting a hypothetical morphological element that is posited as existing by -n-logy with a regular pattern of inflection or derivation in a language, but is not represented by any sequence of phonological elements:
the zero allomorph of “-ed” in “cut”; “deer” has a zero plural.
meteorology.

(of an atmospheric ceiling) pertaining to or limiting vertical visibility to 50 feet (15.2 meters) or less.
of, relating to, or limiting horizontal visibility to 165 feet (50.3 meters) or less.

finance. zero-coupon.
being or pertaining to the precise time, as a specific hour or second, when something must or does happen, as the explosion of a nuclear weapon:
in an underground shelter at zero second.
zero in, to aim (a rifle, etc.) at the precise center or range of a target.
zero in on,

to aim directly at (a target).
to direct one’s attention to; focus on; concentrate on.
to converge on; close in on.

noun (pl) -ros, -roes
the symbol 0, indicating an absence of quant-ty or magnitude; nought former name cipher
the integer denoted by the symbol 0; nought
the cardinal number between +1 and –1
nothing; nil
a person or thing of no significance; nonent-ty
the lowest point or degree: his prospects were put at zero
the line or point on a scale of measurement from which the graduations commence

the temperature, pressure, etc, that registers a reading of zero on a scale
the value of a variable, such as temperature, obtained under specified conditions

a gunsight setting in which accurate allowance has been made for both windage and elevation for a specified range
(maths)

the cardinal number of a set with no members
the ident-ty element of addition

(linguistics)

an allomorph with no phonetic realization, as the plural marker of english sheep
(as modifier): a zero form

(finance) also called zero-coupon bond. a bond that pays no interest, the equivalent being paid in its redemption value compare zebra
adjective
having no measurable quant-ty, magnitude, etc
(meteorol)

(of a cloud ceiling) limiting visibility to 15 metres (50 feet) or less
(of horizontal visibility) limited to 50 metres (165 feet) or less

verb -roes, -roing, -roed
(transitive) to adjust (an instrument, apparatus, etc) so as to read zero or a position taken as zero
determiner
(informal, mainly us) no (thing) at all: this job has zero interest
n.
v.

v.
to adjust an instrument or a device to zero value.
zero
(zîr’ō)
the numerical symbol 0, representing a number that when added to another number leaves the original number unchanged.

our living language : although the origin of zero is controversial, some historians believe that it was invented by the babylonians in about 500 bce. in the sixth century, it was discovered by the hindus and chinese, and 700 years later, it reached the western world via the arabs. zero is the only integer (whole number) that is neither positive nor negative. in a sense, zero makes negative numbers possible, as a negative number added to its positive counterpart always equals zero. when zero is added to or subtracted from a number, it leaves the number at its original value. zero is essential as a position holder in the system known as positional notation. in the number 203, for example, there are two hundreds, zero tens, and three ones. zero indicates that the value of the tens place is zero. in the number 1024, zero indicates that the value of the hundreds place is zero. scientists use the term absolute zero (0° kelvin) to refer to the (unattainable) theoretically lowest possible temperature, at which the kinetic energy of molecules is zero.

a referee or other sports official who wears a striped shirt on the playing field: pro football zebras point immediately toward the offending team/ a crooked zebra (also known as an umpire) (1978+ sports)
an unlikely, arcane, or obscure diagnosis (1980s+ medical)
a person of mixed black and white race: i’ve been called a ”zebra” and an ”oreo” (1980s+)

aim precisely at a target, as in they zeroed in on the last snipers. [ c. 1940 ]
direct one’s attention to, concentrate or focus on, as in we must zero in on the exact combination of ingredients, or the whole cl-ss zeroed in on the new -ssignment. this usage transfers aiming a firearm to directing one’s attention. [ mid-1900s ]
converge on, close in on, as in the children zeroed in on the electric train display. [ mid-1900s ]