/ Dictionary / Index I irrationality: Meaning and Definition of Find definitions for: ir•ra•tion•al•i•ty Pronunciation: (i-rash"u-nal'i-tē), [key] — pl. -ties the quality or condition of being irrational. an irrational, illogical, or absurd action, thought, etc. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: irrationality (Thesaurus) irrationalism irrationalize Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language