ultrahazardous

adjective

ul·​tra·​haz·​ard·​ous ˌəl-trə-ˈha-zər-dəs 

: 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

Legal Definition

ultrahazardous

adjective

ul·​tra·​haz·​ard·​ous

ˌəl-trə-ˈha-zər-dəs

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