/ Dictionary / Index P propylthiouracil: Meaning and Definition of Find definitions for: pro•pyl•thi•o•ur•a•cil Pronunciation: (prō"pil-thī"ō-yoor'u-sil), [key] — n. Pharm. a white crystalline compound, CHNOS, that interferes with the synthesis of thyroid hormone by the thyroid gland: used in the treatment of hyperthyroidism. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: propylthiouracil (Thesaurus) propylphenyl acetate pro rata Related Content Daily Word Quiz: fervor Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language