The Collaborative International Dictionary of English v.0.48:

Overflow \O`ver*flow"\, v. i.
   1. To run over the bounds.
      [1913 Webster]

   2. To be superabundant; to abound. --Rogers.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Overflow \O"ver*flow`\, n.
   1. A flowing over, as of water or other fluid; an inundation.
      --Bacon.
      [1913 Webster]

   2. That which flows over; a superfluous portion; a
      superabundance. --Shak.
      [1913 Webster]

   3. An outlet for the escape of surplus liquid.
      [1913 Webster]

   Overflow meeting, a meeting constituted of the surplus or
      overflow of another audience.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Overflow \O`ver*flow"\, v. t. [imp. & p. p. Overflowed; p. pr.
   & vb. n. Overflowing.] [AS. oferfl?wan. See Over, and
   Flow.]
   1. To flow over; to cover woth, or as with, water or other
      fluid; to spread over; to inundate; to overwhelm.
      [1913 Webster]

            The northern nations overflowed all Christendom.
                                                  --Spenser.
      [1913 Webster]

   2. To flow over the brim of; to fill more than full.
      [1913 Webster]

WordNet (r) 3.0 (2006):

overflow
    n 1: a large flow [syn: flood, overflow, outpouring]
    2: the occurrence of surplus liquid (as water) exceeding the
       limit or capacity [syn: overflow, runoff, overspill]
    v 1: flow or run over (a limit or brim) [syn: overflow,
         overrun, well over, run over, brim over]
    2: overflow with a certain feeling; "The children bubbled over
       with joy"; "My boss was bubbling over with anger" [syn:
       bubble over, overflow, spill over]

Moby Thesaurus II by Grady Ward, 1.0:

179 Moby Thesaurus words for "overflow":
   abound, abundance, affluence, alluvion, alluvium,
   ample sufficiency, ampleness, amplitude, avalanche, bonanza,
   bountifulness, bountiousness, bristle with, bumper crop, cascade,
   cataclysm, cataract, cloud of words, congestion, copiousness,
   crawl with, creep with, deluge, diffuseness, diffusion,
   diffusiveness, drown, effusion, effusiveness, engorgement, engulf,
   engulfment, extravagance, exuberance, exuberate, fecundity,
   fertility, fill, flood, flooding, flow, fluency, foison,
   formlessness, full measure, fullness, generosity, generousness,
   glut, great abundance, great plenty, gush, gushing, hyperemia,
   inundate, inundation, know no bounds, landslide, lavishness,
   liberality, liberalness, logorrhea, lots, luxuriance, luxuriate,
   macrology, maximum, more than enough, much, myriad, myriads,
   numerousness, opulence, opulency, outpour, outpouring, overabound,
   overabundance, overbrim, overbrimming, overburden, overcharge,
   overfill, overflowing, overfreight, overfullness, overgrow,
   overkill, overload, overmuch, overplus, overrun, overrunning,
   overspill, overspread, overswarm, overweight, overwhelm, palilogy,
   plenitude, plenteousness, plentifulness, plenty, pleonasm,
   plethora, pour, pour out, pour over, prevalence, prodigality,
   productiveness, productivity, profuseness, profusion, proliferate,
   prolificacy, prolificity, pullulate, quantities, rain, rampancy,
   rankness, redundancy, reiteration, reiterativeness,
   repetition for effect, repetitiveness, repleteness, repletion,
   rich harvest, rich vein, richness, riot, riotousness, run over,
   run riot, satiety, saturation, scads, shower, slop, slosh, spate,
   spill, spill out, spill over, spillage, stream, submerge,
   submersion, substantiality, substantialness, superabound,
   superabundance, superfluity, superflux, supersaturation, surcharge,
   surfeit, surplus, surplusage, swamp, swarm, swarm with, sweep,
   talkativeness, tautology, teem, teem with, teemingness, the Deluge,
   the Flood, tirade, torrent, washout, wealth, well, whelm,
   whelming



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

overflow

    The condition that occurs when the result of a
   calculation is too big to store in the intended format.  For
   example, the result of adding one to 255 cannot be represented
   as an unsigned, eight-bit integer.  In a signed integer
   representation, overflow can occur when an integer becomes
   either too positive or too negative.

   Overflow can also occur in the exponent of a floating point
   number representation.  The term "underflow" is sometimes
   used for negative overflow of the exponent.

   Ignoring overflow will result in nonsensicle results such as
   255 + 1 = 0.  At the hardware level, the ALU typically
   indicates overflow by setting an overflow flag bit which the
   program can test.  Programming languages will typically
   respond to overflow by raising some kind of signal or other
   error condition to halt normal execution.

   Some languages attempt to avoid overflow by providing
   (optional) variable length number representation
   (multiprecission arithmetic) so that the maximum number
   representable is limited only by the amount of storage
   available.

   (2008-05-30)