/ Dictionary / Index I insufficiency: Meaning and Definition of Find definitions for: in•suf•fi•cien•cy Pronunciation: (in"su-fish'un-sē), [key] — pl. -cies deficiency in amount, force, power, competence, or fitness; inadequacy: insufficiency of supplies. an instance of this. inability of an organ or other part of the body to function normally: cardiac insufficiency. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: insufficiency (Thesaurus) insufferable insufficient 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