/ Dictionary / Index T tachylyte: Meaning and Definition of Find definitions for: tach•y•lyte Pronunciation: (tak'u-līt"), [key] — n. Petrog. a black, glassy form of basalt, readily fusible and of a high luster. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. tachygraphy tachymeter 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