/ Dictionary / Index I immunodeficiency: Meaning and Definition of Find definitions for: im•mu•no•de•fi•cien•cy Pronunciation: (im"yu-nō-di-fish'un-sē, i-my"-), [key] — pl. -cies. impairment of the immune response, predisposing to infection and certain malignancies. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: immunodeficiency (Thesaurus) immunocytochemistry immunodiagnosis 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