The Collaborative International Dictionary of English v.0.48:

Chaos \Cha"os\ (k[=a]"[o^]s), n. [L. chaos chaos (in senses 1 &
   2), Gr. cha`os, fr. cha`inein (root cha) to yawn, to gape, to
   open widely. Cf. Chasm.]
   1. An empty, immeasurable space; a yawning chasm. [Archaic]
      [1913 Webster]

            Between us and there is fixed a great chaos. --Luke
                                                  xvi. 26
                                                  (Rhemish
                                                  Trans.).
      [1913 Webster]

   2. The confused, unorganized condition or mass of matter
      before the creation of distinct and orderly forms.
      [1913 Webster]

   3. Any confused or disordered collection or state of things;
      a confused mixture; confusion; disorder.
      [1913 Webster]

WordNet (r) 3.0 (2006):

chaos
    n 1: a state of extreme confusion and disorder [syn: chaos,
         pandemonium, bedlam, topsy-turvydom, topsy-
         turvyness]
    2: the formless and disordered state of matter before the
       creation of the cosmos
    3: (Greek mythology) the most ancient of gods; the
       personification of the infinity of space preceding creation
       of the universe
    4: (physics) a dynamical system that is extremely sensitive to
       its initial conditions

Moby Thesaurus II by Grady Ward, 1.0:

161 Moby Thesaurus words for "chaos":
   agitation, aloofness, amorphia, amorphism, amorphousness,
   anarchism, anarcho-syndicalism, anarchy, antinomianism,
   astronomical unit, bedlam, befuddlement, bewilderment, blurriness,
   bluster, bother, botheration, brawl, broil, brouhaha, cacophony,
   celestial spaces, cloud, commotion, confusion, cosmic space,
   criminal syndicalism, daze, diffusion, discombobulation,
   discomfiture, discomposure, disconcertion, discontinuity,
   discreteness, disjunction, dislocation, disorder, disorderliness,
   disorganization, disorientation, dispersal, dispersion, disruption,
   dissolution, disturbance, ebullition, embarrassment, embroilment,
   empty space, entropy, ether space, fabulous formless darkness,
   fanaticism, ferment, flap, flummox, flurry, fluster, flutter, fog,
   fomentation, foofaraw, formlessness, foul-up, frenzy, fuddle,
   fuddlement, fume, furor, furore, fury, fuss, fuzziness, hassle,
   haze, haziness, hubbub, incoherence, inconsistency, indecisiveness,
   indefiniteness, indeterminateness, interstellar space, jumble,
   lawlessness, license, light-year, lynch law, maze, mess, messiness,
   metagalactic space, misrule, mist, mistiness, mix-up, mob law,
   mob rule, mobocracy, morass, muddle, muddlement, nihilism,
   nonadhesion, noncohesion, obscurity, ocean of emptiness,
   ochlocracy, orderlessness, outer space, pandemonium, parsec,
   passion, perplexity, perturbation, pother, pressureless space,
   primal chaos, pucker, racket, rage, rebellion, revolution, row,
   ruckus, ruffle, rumpus, scattering, screw-up, separateness,
   shapelessness, shuffle, snafu, space, stew, storminess, sweat,
   swivet, syndicalism, tempestuousness, the void, the void above,
   tizzy, tohubohu, tumult, tumultuousness, turbulence, turmoil,
   unadherence, unadhesiveness, unclearness, unruliness, unsettlement,
   untenacity, uproar, upset, vagueness, wildness, zeal,
   zealousness



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

chaos

    A property of some non-linear dynamic systems
   which exhibit sensitive dependence on initial conditions.
   This means that there are initial states which evolve within
   some finite time to states whose separation in one or more
   dimensions of state space depends, in an average sense,
   exponentially on their initial separation.

   Such systems may still be completely deterministic in that
   any future state of the system depends only on the initial
   conditions and the equations describing the change of the
   system with time.  It may, however, require arbitrarily high
   precision to actually calculate a future state to within some
   finite precision.

   ["On defining chaos", R. Glynn Holt
    and D. Lynn Holt
   .

(ftp://mrcnext.cso.uiuc.edu/pub/etext/ippe/preprints/Phil_of_Science/Holt_and_Holt.On_Defining_Chaos)]

   Fixed precision floating-point arithmetic, as used by most
   computers, may actually introduce chaotic dependence on
   initial conditions due to the accumulation of rounding errors
   (which constitutes a non-linear system).

   (1995-02-07)