/ Dictionary / Index A adiactinic: Meaning and Definition of Find definitions for: a•di•ac•tin•ic Pronunciation: (ā"dī-ak-tin'ik), [key] — adj. (of a medium) not capable of transmitting actinic rays. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. adiabatic chart adiadochokinesia Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language