implacable 10 Associations

grim (similar term) inexorable (similar term) relentless (similar term) stern (similar term) unappeasable (similar term) unforgiving (similar term) unrelenting (similar term)

inflexible 10 Associations

adamant (similar term) adamantine (similar term) inexorable (similar term) intransigent (similar term) die-hard (similar term) rock-ribbed (similar term) fossilized (similar term)