Definition of unmitigable in English:

unmitigable

Pronunciation /(ˌ)ʌnˈmɪtɪɡəbl/

adjective

  • That cannot be mitigated; implacable, uncompromising.

Origin

Early 17th century; earliest use found in William Shakespeare (1564–1616), playwright and poet. Alteration of immitigable, with substitution of un- for the first element.