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no·bel·i·um (nō-bĕlē-əm)
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n. Symbol No
A radioactive transuranic element in the actinide series artificially produced in trace amounts. Its most long-lived isotopes are No-255 with a half-life of 3.1 minutes, and No-259 with a half-life of 58 minutes. Atomic number 102; valence 2, 3. See Periodic Table.

[After Alfred Bernhard Nobel.]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
 

Indo-European & Semitic Roots Appendices

    Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

    Indo-European Roots

    Semitic Roots

    The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.