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pyrophoric

American

[pahy-ruh-fawr-ik, -for-] / ˌpaɪ rəˈfɔr ɪk, -ˈfɒr- /

adjective

Chemistry.

capable of igniting spontaneously in air.

pyrophoric British

/ ˌpaɪrəʊˈfɒrɪk /

adjective

(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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of pyrophoric

1780–90; < Greek pyrophór ( os ) fire-bearing ( pyro-, -phorous ) + -ic

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Defense Department has placed significantly fewer orders for Alloy Surfaces’ pyrophoric airborne decoys, which the company manufactures in Philadelphia and are used as protection against heat-seeking missiles.

From The Wall Street Journal • Nov. 10, 2025

The coal is primarily low-grade, high-polluting lignite, and much of it is pyrophoric, that is to say, it can ignite spontaneously upon contact with oxygen.

From Time Magazine Archive

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023