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]

WordNet (r) 3.0 (2006):

zero
    adj 1: indicating the absence of any or all units under
           consideration; "a zero score" [syn: zero, 0]
    2: having no measurable or otherwise determinable value; "the
       goal is zero population growth"
    3: indicating an initial point or origin
    4: of or relating to the null set (a set with no members)
    n 1: a quantity of no importance; "it looked like nothing I had
         ever seen before"; "reduced to nil all the work we had
         done"; "we racked up a pathetic goose egg"; "it was all for
         naught"; "I didn't hear zilch about it" [syn: nothing,
         nil, nix, nada, null, aught, cipher, cypher,
         goose egg, naught, zero, zilch, zip, zippo]
    2: a mathematical element that when added to another number
       yields the same number [syn: zero, 0, nought, cipher,
       cypher]
    3: the point on a scale from which positive or negative
       numerical quantities can be measured [syn: zero, zero
       point]
    4: the sight setting that will cause a projectile to hit the
       center of the target with no wind blowing
    v 1: adjust (an instrument or device) to zero value
    2: adjust (as by firing under test conditions) the zero of (a
       gun); "He zeroed in his rifle at 200 yards" [syn: zero,
       zero in]

Moby Thesaurus II by Grady Ward, 1.0:

52 Moby Thesaurus words for "zero":
   absolute zero, aught, blank, boiling point, cipher, concentrate on,
   dew point, duck, dud, dummy, fix on, focus on, freezing point,
   goose egg, hollow man, home in on, insignificancy, jackstraw,
   lay figure, man of straw, melting point, nada, nadir, naught,
   nebbish, nichts, nihil, nil, nix, no such thing, nobody, nonentity,
   nothing, nothing at all, nothing on earth, nothing whatever,
   nought, null, nullity, pinpoint, puppet, pushover,
   recalescence point, rock bottom, temperature, thing of naught,
   trifle, void, whiffet, whippersnapper, zero in on, zilch



The Jargon File (version 4.4.7, 29 Dec 2003):

zero
 vt.

    1. To set to 0. Usually said of small pieces of data, such as bits or words
    (esp. in the construction zero out).

    2. To erase; to discard all data from. Said of disks and directories, where
    ?zeroing? need not involve actually writing zeroes throughout the area
    being zeroed. One may speak of something being logically zeroed rather than
    being physically zeroed. See scribble.


The Free On-line Dictionary of Computing (30 December 2018):

ZERO

    An object oriented extension of Z.

   ["Object Orientation in Z", S. Stepney et al eds, Springer
   1992].

   [Jargon File]

   (1995-03-30)


The Free On-line Dictionary of Computing (30 December 2018):

zero
0

   1.  0, ASCI character 48.  Numeric zero, as
   opposed to the letter "O" (the 15th letter of the English
   alphabet).  In their unmodified forms they look a lot alike,
   and various kluges invented to make them visually distinct
   have compounded the confusion.

   If your zero is centre-dotted and letter-O is not, or if
   letter-O looks almost rectangular but zero looks more like an
   American football stood on end (or the reverse), you're
   probably looking at a modern character display (though the
   dotted zero seems to have originated as an option on IBM
   3270 controllers).  If your zero is slashed but letter-O is
   not, you're probably looking at an old-style ASCII graphic
   set descended from the default typewheel on the venerable
   ASR-33 Teletype (Scandinavians, for whom slashed-O is a
   letter, curse this arrangement).

   If letter-O has a slash across it and the zero does not, your
   display is tuned for a very old convention used at IBM and a
   few other early mainframe makers (Scandinavians curse *this*
   arrangement even more, because it means two of their letters
   collide).  Some Burroughs/Unisys equipment displays a zero
   with a *reversed* slash.  And yet another convention common on
   early line printers left zero unornamented but added a tail
   or hook to the letter-O so that it resembled an inverted Q or
   cursive capital letter-O.

   [Jargon File]

   (1995-01-24)

   2. To set to zero.  Usually said of small pieces of data, such
   as bits or words (especially in the construction "zero out").

   3. To erase; to discard all data from.  Said of disks and
   directories, where "zeroing" need not involve actually writing
   zeroes throughout the area being zeroed.  One may speak of
   something being "logically zeroed" rather than being
   "physically zeroed".

   See scribble.

   (1999-02-07)