/ Dictionary / Index M mass hysteria: Meaning and Definition of Find definitions for: mass' hyste'ria Pronunciation: [key] a condition affecting a group of persons, characterized by excitement or anxiety, irrational behavior or beliefs, or inexplicable symptoms of illness. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Massey massicot Related Content Daily Word Quiz: dissonant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language