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[pahy-ruh-fawr-ik, -for-] /ˌpaɪ rəˈfɔr ɪk, -ˈfɒr-/
adjective, Chemistry
capable of igniting spontaneously in air.
1830-40; < Greek pyrophór(os) fire-bearing (see pyro-, -phorous) + -ic Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples for pyrophoric
  • The chemical requires careful handling, because as a pyrophoric, it catches fire when exposed to air.
  • However, this is a pyrophoric reaction and extremely exothermic.
  • Uranium is a heavy, silvery-white metal which is pyrophoric when finely divided.
  • Thus, bulk aluminum is used as a structural metal, but finely divided aluminum is pyrophoric.
  • Finely divided hafnium is pyrophoric and can ignite spontaneously in air.
  • Current slurry hydrogenation catalysts are pyrophoric and must be handled manually.
  • Examples include various pyrophoric metals, self-heating solids, and water-reactive solids.
  • These metals are pyrophoric, ie the burn spontaneously when heated.
  • Powdered thorium metal is often pyrophoric and should be handled carefully.
  • During transfer of the pyrophoric chemical, a syringe came apart and the chemical ignited.
British Dictionary definitions for pyrophoric


(of a chemical) igniting spontaneously on contact with air
(of an alloy) producing sparks when struck or scraped lighter flints are made of pyrophoric alloy
Word Origin
C19: from New Latin pyrophorus, from Greek purophoros fire-bearing, from pur fire + pherein to bear
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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