/ Dictionary / Index A actinia: Meaning and Definition of Find definitions for: ac•tin•i•a Pronunciation: (ak-tin'ē-u), [key] — pl. -tin•i•ae -tin•i•as. a sea anemone, esp. of the genus Actinia. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: actinia (Thesaurus) acting area actinian Related Content Daily Word Quiz: abstain Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language