Implacable means impossible to soften or appease. An implacable enemy, implacable opposition, implacable in his hostility.
It is admiring as often as it is fearful, since implacable opposition is what a cause needs from its own side. It is built on the same root as placate, so an implacable person is one nobody can placate.
1adjectiveimplacableImpossible to soften or appease.
“She faced an implacable enemy who would never accept her apology.”
implacable is a quality.
In- is not, and the rest is Latin for to placate. Somebody implacable cannot be placated: nothing calms them and nothing ends it.
hooks ontoplacate
Latin implacabilis is in-, not, plus placare, to soothe, the root of placate.
Latin
implācābilis — unappeasable, implacable; irreconcilable
Old French
implacable — harsh, unrelenting; implacable
Middle English
implācāble — immitigable, unappeasable
English, today
implacable
Built from
From Middle English implācāble (“immitigable, unappeasable”) from Old French implacable (“harsh, unrelenting; implacable”) (modern French implacable), from Latin implācābilis (“unappeasable, implacable; irreconcilable”), from im- (variant of in-) + plācābilis (“placable; appeasing, moderating, pacifying, propitiating; acceptable”) (from plācō (“to assuage, pacify, placate; to appease; to reconcile”) + -bilis).
Etymology from Wiktionary, CC BY-SA