/ Dictionary / Index A actinic: Meaning and Definition of Find definitions for: ac•tin•ic Pronunciation: (ak-tin'ik), [key] — adj. pertaining to actinism. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: actinic (Thesaurus) actinian actinic ray Related Content Daily Word Quiz: reclusive Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language