/ Dictionary / Index D developmental psychology: Meaning and Definition of Find definitions for: developmen'tal psychol'ogy Pronunciation: [key] a branch of psychology that studies changes in human behavior from early life to death. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. developmentalist development rights Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language