Breadcrumb Home > Thesaurus > A Synonyms of actinium Find synonyms for: Noun 1. actinium, Ac, atomic number 89, chemical element, element usage: a radioactive element of the actinide series; found in uranium ores WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of actinium (Dictionary) TrendingHere are the facts and trivia that people are buzzing about. Did Birds Evolve from Dinosaurs? The Twelve Dancing Princesses Current Events This Week: January 2023 African Americans by the Numbers Andersen's Fairy Tales: Contents The Celtic Twilight: A Teller of Tales ✖ Related Content Daily Word Quiz: limpid Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language