[1] : The Collaborative International Dictionary of English v.0.48

surplus \sur"plus\, n. f., fr. sur over + plus more. see
   sur-, and plus, and cf. superplus.
   1. that which remains when use or need is satisfied, or when
      a limit is reached; excess; overplus.
      1913 webster

   2. specifically, an amount in the public treasury at any time
      greater than is required for the ordinary purposes of the
      government.
      1913 webster
see also:
sur- plus superplus 

[2] : The Collaborative International Dictionary of English v.0.48

surplus \sur"plus\, a.
   being or constituting a surplus; more than sufficient; as,
   surplus revenues; surplus population; surplus words.
   1913 webster

         when the price of corn falleth, men give over surplus
         tillage, and break no more ground.       --carew.
   1913 webster

[3] : WordNet (r) 2.0

surplus
     adj : more than is needed, desired, or required; "trying to lose
           excess weight"; "found some extra change lying on the
           dresser"; "yet another book on heraldry might be
           thought redundant"; "skills made redundant by
           technological advance"; "sleeping in the spare room";
           "supernumerary ornamentation"; "it was supererogatory
           of her to gloat"; "delete superfluous or unnecessary
           words"; "extra ribs as well as other supernumerary
           internal parts"; "surplus cheese distributed to the
           needy" syn: excess, extra, redundant, spare, supererogatory,
            superfluous, supernumerary
     n : a quantity much larger than is needed syn: excess, surplusage,
          nimiety
see also:
excess extra redundant spare supererogatory superfluous 
supernumerary surplusage nimiety 

[4] : Moby Thesaurus II by Grady Ward, 1.0

127 moby thesaurus words for "surplus":
   accessory, additional, ancillary, another, as a bonus, auxiliary,
   balance, bonus, boot, bounce, break, bump, bust, can, cashier,
   collateral, contributory, credit, de trop, deficiency, deficit,
   defrock, degrade, demote, deplume, depose, deprive, difference,
   disbar, discharge, discrepancy, disemploy, dismiss, displace,
   displume, dividend, drum out, epact, exaggeration, excess, expel,
   extra, farther, fire, for lagniappe, fresh, furlough, further,
   give the ax, give the gate, glut, gratuity, inundation, kick,
   kick upstairs, lagniappe, lay off, left, leftover, leftovers,
   let go, let out, make redundant, margin, more, net, new, odd,
   other, outstanding, over, over and above, overabundance, overage,
   overdose, overflow, overflowing, overgrowth, overkill, overmeasure,
   overmuch, overpass, overplus, overrun, overrunning, overset,
   overspreading, overstock, oversupply, pension off, plethora, plus,
   pourboire, read out of, redundancy, redundant, release, remainder,
   remaining, remanent, remove, replace, retire, sack,
   separate forcibly, something extra, spare, strip, superannuate,
   superfluity, superfluous, superiority, supernumerary, supplemental,
   supplementary, surfeit, surplusage, surviving, suspend, tip,
   to spare, turn off, turn out, ulterior, unconsumed, unfrock,
   unused

Surplus >> S Words
Surplus, definition of term: Surplus
surplus_pag1.html