implacable
- adjective (adj)
Meaning: merciless, cruel
Synonyms:
grim
inexorable
inflexible
intractable
ironfisted
mortal
pitiless
rancorous
relentless
remorseless
ruthless
unappeasable
unbending
uncompromising
unflinching
unforgiving
unrelenting
unyielding
vindictive
Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.