/ Dictionary / Index H hyperexcitability: Meaning and Definition of Find definitions for: hy•per•ex•cit•a•bil•i•ty Pronunciation: (hī"pur-ik-sī"tu-bil'i-tē), [key] — n. Pathol., Psychol. an excessive reaction to stimuli. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. hypereutectoid hyperextension Related Content Daily Word Quiz: impetuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language