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o·gan·es·son(ə-găn′ə-sŏn′, ô′gə-nĕs′ŏn, -ən)
n. Symbol Og
An artificially produced radioactive element with atomic number 118, whose most stable isotope has a mass number of 294 and a half-life of 1.3 milliseconds.
[oganess- (after Yuri Oganessian (born 1933), Russian nuclear physicist and scientific director at the Joint Institute for Nuclear Research in Dubna, where the element was first synthesized) + -on.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.