/ Dictionary / Index T thio acid: Meaning and Definition of Find definitions for: thi'o ac'id Pronunciation: [key] — Chem. Chem. an acid in which part or all of the oxygen has been replaced by sulfur. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. thioacetic acid thioaldehyde Related Content Daily Word Quiz: labyrinth Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language