The Collaborative International Dictionary of English v.0.48:

Sum \Sum\, v. t. [imp. & p. p. Summed; p. pr. & vb. n.
   Summing.] [Cf. F. sommer, LL. summare.]
   1. To bring together into one whole; to collect into one
      amount; to cast up, as a column of figures; to ascertain
      the totality of; -- usually with up.
      [1913 Webster]

            The mind doth value every moment, and then the hour
            doth rather sum up the moments, than divide the day.
                                                  --Bacon.
      [1913 Webster]

   2. To bring or collect into a small compass; to comprise in a
      few words; to condense; -- usually with up.
      [1913 Webster]

            "Go to the ant, thou sluggard," in few words sums up
            the moral of this fable.              --L'Estrange.
      [1913 Webster]

            He sums their virtues in himself alone. --Dryden.
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   3. (Falconry) To have (the feathers) full grown; to furnish
      with complete, or full-grown, plumage.
      [1913 Webster]

            But feathered soon and fledge
            They summed their pens [wings].       --Milton.
      [1913 Webster]

   Summing up, a compendium or abridgment; a recapitulation; a
      r['e]sum['e]; a summary.
      [1913 Webster]

   Syn: To cast up; collect; comprise; condense; comprehend;
        compute.
        [1913 Webster] Sumac

WordNet (r) 3.0 (2006):

summing up
    n 1: a concluding summary (as in presenting a case before a law
         court) [syn: summation, summing up, rundown]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "summing up":
   account, accounts, argument, body count, capitulation, census,
   copy, count, critique, dwelling upon, elaboration, epitome,
   evidence, going over, head count, inventory, iteration, nose count,
   practicing, reaffirmation, recap, recapitulation, recital,
   reckoning, recount, recountal, recounting, rehash, rehearsal,
   reissue, reiteration, repertory, reprint, restatement, resume,
   retelling, review, statement, sum, summary, summation, summing,
   testimony



Bouvier's Law Dictionary, Revised 6th Ed (1856):

SUMMING UP, practice. The act of making a speech before a court and jury,
after all the evidence has been heard, in favor of one of the parties in the
cause, is called summing up. When the judge delivers his charge to the jury,
he is also said to sum up the evidence in the case. 6 Harg. St. Tr. 832; 1
Chit. Cr. Law, 632.
     2. In summing up, the judge should, with much precision and clearness,
state the issues joined between the parties, and what the jury are required
to find, either in the affirmative or negative. He should then state the
substance of the plaintiff's claim and of the defendant's ground of defence,
and so much of the evidence as is adduced for each party, pointing out as he
proceeds, to which particular question or issue it respectively applies,
taking care to abstain as much as possible from giving an opinion as to the
facts. It is his duty clearly to state the law arising in the case in such
terms as to leave no doubt as to his meaning, both for the purpose of
directing the jury, and with a view of correcting, on a review of the case
on a motion for a new trial, or on a writ of error, any error he may, in the
hurry of the trial, have committed. Vide 8 S. & R. 150; 1 S. & R. 515; 4
Rawle, R. 100, 195, 356; 2 Penna. R. 27; 2 S. & R. 464. Vide Charge;
Opinion, (Judgment.)