nouns
a quantity of money
"he borrowed a large sum"; "the amount he had in cash was insufficient"
a quantity obtained by the addition of a group of numbers
the final aggregate
"the sum of all our troubles did not equal the misery they suffered"
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"
center,
centre,
core,
essence,
gist,
heart,
heart and soul,
inwardness,
kernel,
marrow,
meat,
nitty-gritty,
nub,
pith,
substance,
sum
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"