partial sum

noun Mathematics.

one of a series of sums of elements of a given sequence, the first sum being the first element, the second sum being the first element added to the second element, the third sum being equal to the sum of the first three elements, and so on.

Origin of partial sum

First recorded in 1925–30

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018