/ Dictionary / Index V vastus: Meaning and Definition of Find definitions for: vas•tus Pronunciation: (vas'tus), [key] — pl. -ti any of several muscles in the front part of the thigh constituting part of the quadriceps muscle, the action of which assists in extending the leg. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. vastity vasty Related Content Daily Word Quiz: nonchalant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language