/ Dictionary / Index A actinian: Meaning and Definition of Find definitions for: ac•tin•i•an Pronunciation: (ak-tin'ē-un), [key] — adj. belonging or pertaining to the order or suborder Actiniaria, comprising the sea anemones. —n. any sea anemone. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: actinian (Thesaurus) actinia actinic 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