Nouns

(n)sum, sum of money, amount, amount of moneya quantity of money“he borrowed a large sum”, “the amount he had in cash was insufficient”
(n)sum, amount, totala quantity obtained by the addition of a group of numbers
(n)sum, summation, sum totalthe final aggregate“the sum of all our troubles did not equal the misery they suffered”
(n)kernel, substance, core, center, centre, essence, gist, heart, heart and soul, inwardness, marrow, meat, nub, pith, sum, nitty-grittythe 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”
(n)sum, total, totality, aggregatethe whole amount
(n)union, sum, joina set containing all and only the members of two or more given sets“let C be the union of the sets A and B”

Verbs

(v)summarize, summarise, sum, sum upbe a summary of“The abstract summarizes the main ideas in the paper”
(v)total, tot, tot up, sum, sum up, summate, tote up, add, add together, tally, add updetermine the sum of“Add all the people in this town to those of the neighboring town”