/ Dictionary / Index I isabnormal: Meaning and Definition of Find definitions for: is•ab•nor•mal Pronunciation: (ī"sab-nôr'mul), [key] — n. Meteorol. a line on a map or chart connecting points having an equal deviation from the normal value of some meteorological quantity, as temperature. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Isabella I isacoustic Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language