Definition of sum in English:
sum
Line breaks: sumPronunciation: /sʌm
/
noun
 1A particular amount of money: they could not afford such a sumMore example sentences
 Is it right to spend vast sums of money funding expensive conferences?
 Most Japanese currently hold large sums of money in secure savings accounts that yield zero interest.
 The conman asks the person contacted to contribute a small sum of money to speed up the release of the funds.
 2 (the sum of) The total amount resulting from the addition of two or more numbers, amounts, or items: the sum of two prime numbersMore example sentences
 A perfect number is defined to be one which is equal to the sum of its aliquot parts.
 In fact the Egyptians only had fractions of this type and if the answer had not involved a unit fraction then the Egyptians would have written the fractional part as the sum of unit fractions.
 Find a right triangle having the property that the hypotenuse equals the sum of one leg plus the altitude on the hypotenuse.
 2.1The total amount of something that exists: the sum of his own knowledgeMore example sentences
 Tipped to tumble, Motherwell now surf the wave of just one loss in six games thanks to an unexpected capacity to maximise the sum of their unremarkable talents and convert it resolutely into a winning equation.
 It's because critics of homosexuality just can't see the sum of human perfection that is gayness and all its works and ways.
 The Bellini is an idea not the sum of its content.
entirety, totality, total, whole, aggregate, summation, beginning and end, alpha and omega, beall and endall• informal whole shebang, whole caboodle, whole shooting match, {lock, stock, and barrel}
 3An arithmetical problem, especially at an elementary level: we did sums at school, Mummy do your sums, then the shock will not be too greatMore example sentences
 You saw crates of certain sizes, and then you would do your sums and then do your deductions from that.
 Have you ever wondered why your children seem to do their sums upsidedown nowadays?
 She said: ‘I still have to do my sums and see if it is still a possibility for me.’
arithmetical problem, problem, calculation, reckoning, tally, question; (sums) arithmetic, mathematics, figures, numbers, computationBritish • informal mathsNorth American • informal math
verb
( sums, summing, summed)
 • technical Find the sum of (two or more amounts): if we sum these equations we obtain XMore example sentences
 The amount of total nonstructural carbohydrates was calculated by summing the amount of starch and soluble sugar.
 Functional group abundance was calculated by summing the abundances of all species in a particular group on a sample date.
 He found the length of an arc of the cycloid using an exhaustion proof based on dissections to reduce the problem to summing segments of chords of a circle which are in geometric progression.
Phrases

in sum
 To sum up: this interpretation does little, in sum, to add to our understandingMore example sentences
 So in sum: yes, the blasé reaction to Wolff's article does reflect a moderating of stances on sexual harassment, but don't gloat about it; the pendulum is still very much on the left, no matter how much you might want it to be otherwise.
 If you believe in cultural relativism, or that crime should not be followed by punishment, or that our borders should be thrown open  in sum if you oppose traditional institutions and values  you are hardly in the mainstream.
 So, in sum, if you like Musical Barbeque, you'll probably like this, and if you don't like Musical Barbeque, well, I'm not so sure I want you reading this blog, quite frankly.
in short, briefly, in brief, to put it briefly, to cut a long story short, in a word, to sum up, in a nutshell, to come to the point, in essence, in outline
Phrasal verbs

sum up
 Give a brief summary: Gerard will open the debate and I will sum upMore example sentences
 And those brief details sum up half a century in the life of Bobby Bell, so little is known about him.
 Andrew Gimson in the Telegraph sums up precisely what this means for the election.
 This comment precisely sums up what is expected of a historian when he writes down a narration or a report or a book.
 Law (Of a judge) review the evidence at the end of a case and direct the jury regarding points of law: he was summing up on day two of a historic test caseMore example sentences
 As the learned judge said in his summing up to the jury, motive is irrelevant; intention is important.
 It was therefore rather surprising to me when His Honour Judge Denison summed up to the jury that any military use would do.
 Judge Russell then sums up the facts and the arguments presented to the jury.
summarize the evidence, review the evidence, give a summingup, summarize the argument 
sum someone/thing up
 Concisely describe of the nature or character of someone or something: selfish—that summed her upMore example sentences
 However, she hopes she would be more realistic than Ranevskaya, though she likes her character, summing her up as ‘complex, vulnerable, selfish, very flawed, hopefully charming but emotionally all over the shop’.
 Asked to describe Armenian music, Montreal singer Lousnak sums it up in a single word.
 These characteristics can be summed up as elegance, if you want just one word, but their real character is drinkability.
Origin
Middle English: via Old French from Latin summa 'main part, sum total', feminine of summus 'highest'.
More definitions of sum
Definition of sum in: The US English dictionary
 The English Synonyms
 The US English Synonyms