/ Dictionary / Index A actiniform: Meaning and Definition of Find definitions for: ac•tin•i•form Pronunciation: (ak-tin'u-fôrm"), [key] — adj. Zool. having a radiate form. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. actinide series actinin Related Content Daily Word Quiz: agitated Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language