
union, sum, join  a set containing all and only the members of two or more given sets  

amount, sum, sum of money, amount of money  a quantity of money  

total, sum, aggregate, totality  the whole amount  

center, substance, core, heart, essence, sum, centre, inwardness, marrow, kernel, gist, heart and soul, meat, nub, pith, nittygritty  the choicest or most essential or most vital part of some idea or experience  

sum, summation, sum total  the final aggregate  
V2 
total, add up, add, tot up, summate, add together, tot, sum, sum up, tote up, tally  determine the sum of  

amount, total, sum  a quantity obtained by the addition of a group of numbers  
V2 
sum, sum up, summarize, summarise  be a summary of 