/ Thesaurus / S Synonyms of strontium 90 Find synonyms for: Noun1. strontium 90, strontium, Sr, atomic number 38usage: a radioactive isotope of strontium (with the mass number 90) that is present in the fallout from nuclear explosions; can be assimilated like calcium into bonesWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: labyrinth Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language