/ Dictionary / Index I infantile autism: Meaning and Definition of Find definitions for: in'fantile au'tism Pronunciation: [key] — Psychol. Psychol. a disorder appearing in children before the age of two and a half, characterized by lack of interest in others, impaired communication skills, and bizarre behavior, as ritualistic acts and excessive attachment to objects. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. infantile infantile paralysis Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language