ul·​tra·​haz·​ard·​ous ˌəl-trə-ˈha-zər-dəs How to pronounce ultrahazardous (audio)
: involving an extremely large risk (as of loss or harm) : extremely or extraordinarily hazardous
ultrahazardous waste
Under American law, in all likelihood, the operation of this plant to manufacture methyl isocyanate would be classified as an ultrahazardous activity …William J. Curran

Word History

First Known Use

1886, in the meaning defined above

Time Traveler
The first known use of ultrahazardous was in 1886

Dictionary Entries Near ultrahazardous

Cite this Entry

“Ultrahazardous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ultrahazardous. Accessed 12 Apr. 2024.

Legal Definition


: being of such extreme danger or risk of harm that strict liability will be imposed

More from Merriam-Webster on ultrahazardous

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