/ Dictionary / Index T tonicity: Meaning and Definition of Find definitions for: to•nic•i•ty Pronunciation: (tō-nis'i-tē), [key] — n. tonic quality or condition. the state of bodily tone. the normal elastic tension of living muscles, arteries, etc., by which the tone of the system is maintained. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: tonicity (Thesaurus) tonic accent tonic sol-fa 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