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

summation \summa"tion\, n. cf. f. sommation. see sum, v. t.
   the act of summing, or forming a sum, or total amount; also,
   an aggregate.
   1913 webster

         of this series no summation is possible to a finite
         intellect.                               --de quincey.
   1913 webster
see also:
sum 

[2] : WordNet (r) 2.0

summation
     n 1: a concluding summary as in presenting a case before a law
          court syn: summing up, rundown
     2: physiology the process whereby multiple stimuli can
        produce a response in a muscle or nerve or other part
        that one stimulus alone does not produce
     3: the final aggregate; "the sum of all our troubles did not
        equal the misery they suffered" syn: sum, sum total
     4: the arithmetic operation of summing; calculating the sum of
        two or more numbers; "the summation of four and three
        gives seven"; "four plus three equals seven" syn: addition,
         plus
see also:
summing up rundown sum sum total addition plus 

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

77 moby thesaurus words for "summation":
   abbreviation, abridgment, abstract, account, accounts, addend,
   aggregate, amount, apocope, argument, body count, box score,
   capitulation, cast, census, compression, condensation, conspectus,
   core, count, curtailment, difference, elision, ellipsis, epitome,
   essence, evidence, foreshortening, gist, head count, inventory,
   main point, meat, nose count, number, pith, plus, plus sign,
   precis, product, quantity, recap, recapitulation, reckoning,
   recount, recounting, reduction, rehearsal, repertory, resume,
   retrenchment, run-through, rundown, score, shortening, statement,
   substance, subtotal, sum, sum and substance, summary, summing,
   summing up, summing-up, syncope, synopsis, tale, tally,
   telescoping, testimony, the bottom line, the story,
   the whole story, total, truncation, whole, x number

Summation >> S Words
Summation, definition of term: Summation
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