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. Chinese New Year History, Meaning, and Celebrations Current Events This Week: February 2024 Valentine's Day Valentine's Day History Mardi Gras 30 "Charlie and the Chocolate Factory" Quotes ✖ Related Content Daily Word Quiz: quisling Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language