immitigable
adjective
im·mit·i·ga·ble (ˌ)i(m)-ˈmi-ti-gə-bəl 
: not capable of being mitigated
immitigably
(ˌ)i(m)-ˈmi-ti-gə-blē
adverb 
Example Sentences
Recent Examples on the Web After one of her most affecting passages, Allen walked calmly back to her place in a circle, preparing to hear out Lawson, who gives the final and most harrowing disclosure of the piece, a tale of soured love, horror, and immitigable loss. 
Vinson Cunningham, The New Yorker, 28 Oct. 2019
Vinson Cunningham, The New Yorker, 28 Oct. 2019 Word History
Etymology
Late Latin immitigabilis, from Latin in- + mitigare to mitigate
First Known Use
1576, in the meaning defined above