from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A synthetic transuranic element first produced by neutron irradiation of uranium in a thermonuclear explosion and now usually produced in the laboratory by irradiating plutonium and other elements. The isotopes with the longest half-lives are Es-252 (472 days) and Es-254 (276 days). Atomic number 99; melting point 860°C (estimated); valence 2, 3. cross-reference: Periodic Table.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun a transuranic chemical element (symbol Es) with atomic number 99.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a radioactive transuranic element produced by bombarding plutonium with neutrons


from The American Heritage® Dictionary of the English Language, 4th Edition

[After Albert Einstein.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

Einstein +‎ -ium. Named for Albert Einstein.


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  • Don't expect much, after all these are the people behind elements like californium and einsteinium.

    Something Awful

  • We are not including words coming from the names of particular people, like einsteinium, watt, curium, henry, and other eponyms: we refer here only to first names that have acquired meanings of their own or that, by association, have acquired special connotations.

    VERBATIM: The Language Quarterly Vol VIII No 2

  • I really hope that’s just slang and it has a real-sounding name because I’m just now getting used to einsteinium.

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  • Es.

    December 16, 2007

  • They're renaming this one, because as it turns out, Albert Einstein wasn't nearly so amazingly smart. Starting in 2010 this element will be known as uselessnessium.

    December 17, 2007

  • Sometimes well-deserved recognition is so long in coming.

    That Einstein guy was pretty daft, really.

    December 17, 2007

  • I think calling it Inutilium would be klassier.

    December 17, 2007

  • Plus uselessness has better hair. Or so I've heard. ;-)

    December 18, 2007

  • Well, who doesn't? I mean, if that's the criterion, we might as well call it everybodybuteinsteinium.

    December 18, 2007

  • Depending on the photo, Einstein bears a rather disturbing resemblance to one of my brothers. So maybe everybodybuteinsteinandreeseteesbrotherium.

    I'm just saying.

    December 18, 2007

  • "Well, who doesn't? I mean, if that's the criterion, we might as well call it everybodybuteinsteinium."

    This is the best comment ever.

    December 18, 2007