/ Dictionary / Index A Alum Rock: Meaning and Definition of Find definitions for: Al'um Rock' Pronunciation: (al'um), [key] a town in W central California, near San Jose. 16,890. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. alumnus alumroot Related Content Daily Word Quiz: sedentary Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language