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1. An unstable, poisonous allotrope of oxygen, O3, that is formed naturally in the ozone layer from atmospheric oxygen by electric discharge or exposure to ultraviolet radiation, also produced in the lower atmosphere by the photochemical reaction of certain pollutants. It is a highly reactive oxidizing agent used to deodorize air, purify water, and treat industrial wastes.
2. Informal Fresh, pure air.

[German Ozon, from Greek ozon, neuter present participle of ozein, to smell.]

o·zo′nic (ō-zō′nĭk, ō-zŏn′ĭk), o′zon′ous (ō′zō′nəs) adj.
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.
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He has been called both a "philosophical squirrel" and a "butterfly," described as a "logical acrobat" and "tautology-monger," but also as "empty and aimless"; his skills have been likened to those of a midwife or a dentist, while his style of thinking was depicted as "ozonous." Some of his contemporaries found him brilliant (but like a fireworks that left nothing behind) and others thought he was thoroughly bourgeois, while he is known to have referred to himself as a "fin-de-sieclist." What is beyond dispute is that Simmel was a "fox" rather than a "hedgehog," who relied on a searchlight but never a bucket (to borrow Isaiah Berlin's and Karl Popper's analogies).