/ Thesaurus / A Synonyms of atomic number 93 Find synonyms for: Noun1. neptunium, Np, atomic number 93, metallic element, metalusage: a radioactive transuranic metallic element; found in trace amounts in uranium ores; a by-product of the production of plutoniumWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: confectionery Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language