/ Dictionary / Index P partial sum: Meaning and Definition of Find definitions for: par'tial sum' Pronunciation: [key] — Math. Math. 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. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. partial score partial tone Related Content Daily Word Quiz: deleterious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language