• synonyms


[yoo-nil-kwod-ee-uh m]
noun Chemistry, Physics.
  1. former name of rutherfordium. Symbol: Unq
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Origin of unnilquadium

1975–80; < Latin ūn(us) one + nīl nothing + quad(ri)- + New Latin -ium -ium
Also called element 104.


[ruhth-er-fawr-dee-uh m, -fohr-, ruhth-]
noun Chemistry, Physics.
  1. a superheavy, synthetic, radioactive element with a very short half-life. Symbol: Rf; atomic number: 104.
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Origin of rutherfordium

1969; named after English physicist Ernest Rutherford; see -ium
Formerly unnilquadium, element 104.

element 104

noun Chemistry, Physics.
  1. rutherfordium.
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Origin of element 104

First recorded in 1975–80
Formerly unnilquadium.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for unnilquadium


  1. a transactinide element produced by bombarding californium-249 nuclei with carbon-12 nuclei. Symbol: Rf; atomic number.: 104; atomic wt: 261Name in the former Soviet Union: kurchatovium
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Word Origin

C20: named after Ernest Rutherford
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

unnilquadium in Science


  1. A synthetic, radioactive element that is produced by bombarding plutonium with carbon or neon ions. Its most stable isotope is Rf 261 with a half-life of 62 seconds. Atomic number 104. See Periodic Table.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.