/ Thesaurus / A Synonyms of atomic number 55 Find synonyms for: Noun1. cesium, caesium, Cs, atomic number 55, metallic element, metalusage: a soft silver-white ductile metallic element (liquid at normal temperatures); the most electropositive and alkaline metalWordNet 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