(sum) noun
1. The result obtained by addition.
2. The entire quantity, number, or substance; the whole; all: the sum total of my means; the sum and substance of the case.
3. Any indefinite amount: said chiefly of money.
4. A problem in arithmetic propounded for solution.
5. The summit; topmost or highest point; also, the maximum; the complement.
6. A summary; the pith or essence. See synonyms under AGGREGATE.
—v. summed, sum·ming v.t.
1. To present in brief; recapitulate succinctly: usually with up: to sum up evidence.
2. To add into one total; ascertain the sum of: often with up.
3. To ascertain the sum of (the terms of a series).
—v.i.
4. To make a summation or recapitulation: generally with up. ♦ Homophone: some. [<AF, OF summe, somme <L summa (res) highest (thing), fem. of summus highest]

Assimilated var. of SUB–.