The Collaborative International Dictionary
Unremorseless
Unremorseless \Un`re*morse"less\, a. [Pref. un- not (intensive)
+ remorseless.]
Utterly remorseless. [Obs. & R.] ``Unremorseless death.''
--Cowley.
Wiktionary
unremorseless
a. (context obsolete rare English) Utterly remorseless.