/ Dictionary / Index H hypothyroidism: Meaning and Definition of Find definitions for: hy•po•thy•roid•ism Pronunciation: (hī"pu-thī'roi-diz"um), [key] — n. Pathol. deficient activity of the thyroid gland. the condition produced by a deficiency of thyroid secretion, resulting in goiter, myxedema, and, in children, cretinism. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: hypothyroidism (Thesaurus) hypothetico-deductive method hypotonic Related Content Daily Word Quiz: profiterole Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language