/ Dictionary / Index D decision tree: Meaning and Definition of Find definitions for: deci'sion tree" Pronunciation: [key] — Logic. Logic. a tree diagram in which the selection of each branch requires that some type of logical decision be made. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. decision theory decisive Related Content Daily Word Quiz: reclusive Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language