The Collaborative International Dictionary of English v.0.48:

Sum \Sum\, n. [OE. summe, somme, OF. sume, some, F. somme, L.
   summa, fr. summus highest, a superlative from sub under. See
   Sub-, and cf. Supreme.]
   1. The aggregate of two or more numbers, magnitudes,
      quantities, or particulars; the amount or whole of any
      number of individuals or particulars added together; as,
      the sum of 5 and 7 is 12.
      [1913 Webster]

            Take ye the sum of all the congregation. --Num. i.
                                                  2.
      [1913 Webster]

   Note: Sum is now commonly applied to an aggregate of numbers,
         and number to an aggregate of persons or things.
         [1913 Webster]

   2. A quantity of money or currency; any amount, indefinitely;
      as, a sum of money; a small sum, or a large sum. "The sum
      of forty pound." --Chaucer.
      [1913 Webster]

            With a great sum obtained I this freedom. --Acts
                                                  xxii. 28.
      [1913 Webster]

   3. The principal points or thoughts when viewed together; the
      amount; the substance; compendium; as, this is the sum of
      all the evidence in the case; this is the sum and
      substance of his objections.
      [1913 Webster]

   4. Height; completion; utmost degree.
      [1913 Webster]

            Thus have I told thee all my state, and brought
            My story to the sum of earthly bliss. --Milton.
      [1913 Webster]

   5. (Arith.) A problem to be solved, or an example to be
      wrought out. --Macaulay.
      [1913 Webster]

            A sum in arithmetic wherein a flaw discovered at a
            particular point is ipso facto fatal to the whole.
                                                  --Gladstone.
      [1913 Webster]

            A large sheet of paper . . . covered with long sums.
                                                  --Dickens.
      [1913 Webster]

   Algebraic sum, as distinguished from arithmetical sum, the
      aggregate of two or more numbers or quantities taken with
      regard to their signs, as + or -, according to the rules
      of addition in algebra; thus, the algebraic sum of -2, 8,
      and -1 is 5.

   In sum, in short; in brief. [Obs.] "In sum, the gospel . .
      . prescribes every virtue to our conduct, and forbids
      every sin." --Rogers.
      [1913 Webster]

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.
      [1913 Webster]

   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):

sum
    n 1: a quantity of money; "he borrowed a large sum"; "the amount
         he had in cash was insufficient" [syn: sum, sum of
         money, amount, amount of money]
    2: a quantity obtained by the addition of a group of numbers
       [syn: sum, amount, total]
    3: the final aggregate; "the sum of all our troubles did not
       equal the misery they suffered" [syn: sum, summation,
       sum total]
    4: the choicest or most essential or most vital part of some
       idea or experience; "the gist of the prosecutor's argument";
       "the heart and soul of the Republican Party"; "the nub of the
       story" [syn: kernel, substance, core, center,
       centre, essence, gist, heart, heart and soul,
       inwardness, marrow, meat, nub, pith, sum, nitty-
       gritty]
    5: the whole amount [syn: sum, total, totality,
       aggregate]
    6: a set containing all and only the members of two or more
       given sets; "let C be the union of the sets A and B" [syn:
       union, sum, join]
    v 1: be a summary of; "The abstract summarizes the main ideas in
         the paper" [syn: summarize, summarise, sum, sum up]
    2: determine the sum of; "Add all the people in this town to
       those of the neighboring town" [syn: total, tot, tot
       up, sum, sum up, summate, tote up, add, add
       together, tally, add up]

Moby Thesaurus II by Grady Ward, 1.0:

172 Moby Thesaurus words for "sum":
   account, add, add up, addend, affective meaning, aggregate, all,
   amount, amount of money, amplitude, batch, be-all and end-all,
   bearing, body, box score, budget, bulk, bunch, cast, cast up,
   chunk, cipher up, clutch, coloring, compute, condense, connotation,
   consequence, core, count, count up, deal, denotation, detail,
   difference, digest, dose, drift, effect, entirety, entity, epitome,
   essence, extension, extent, figure, figure up, foot, foot up,
   force, gist, gob, grammatical meaning, grand total, gross,
   gross amount, group, heap, hunk, idea, impact, implication, import,
   integral, integrate, intension, inventory, itemize, large amount,
   lexical meaning, literal meaning, lot, lump sum, magnitude,
   main point, mass, matter, meaning, measure, measurement, meat,
   mess, number, numbers, nutshell, overtone, pack, parcel, part,
   pertinence, pith, plus, plus sign, point, portion,
   practical consequence, product, purport, quantity, quantum,
   range of meaning, ration, real meaning, recap, recapitulate,
   recapitulation, recite, reckon up, reckoning, recount, reference,
   referent, rehearse, relate, relation, relevance, resume, round sum,
   run-through, rundown, scope, score, score up, semantic cluster,
   semantic field, sense, significance, signification, significatum,
   signifie, small amount, span of meaning, spirit, strength,
   structural meaning, structure, substance, subtotal,
   sum and substance, sum total, sum up, summarize, summary, summate,
   summation, summing-up, symbolic meaning, synopsize, system, tale,
   tally, tally up, tenor, the amount, the bottom line, the story,
   the whole story, tot, tot up, total, total up, totality,
   totality of associations, tote, tote up, transferred meaning,
   unadorned meaning, undertone, value, whole, whole amount,
   x number



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

sum

   1.  In domain theory, the sum A + B of two domains
   contains all elements of both domains, modified to indicate
   which part of the union they come from, plus a new bottom
   element.  There are two constructor functions associated with
   the sum:

   	inA : A -> A+B       inB : B -> A+B
   	inA(a) = (0,a)	     inB(b) = (1,b)

   and a disassembly operation:

   	case d of isA(x) -> E1; isB(x) -> E2

   This can be generalised to arbitrary numbers of domains.

   See also smash sum, disjoint union.

   2.  A Unix utility to calculate a 16-bit checksum of
   the data in a file.  It also displays the size of the file,
   either in kilobytes or in 512-byte blocks.  The checksum may
   differ on machines with 16-bit and 32-bit ints.

   Unix manual page: sum(1).

   (1995-03-16)