Implacable

WORD OF THE DAY

implacable / adjective / im-PLAK-uh-bul

Definition
: not placable
: not capable of being appeased, significantly changed, or mitigated

Examples
"His fellow cavers called Mr. [Marion] Smith 'the Goat,' and he certainly looked the part, with a compact, wiry body and a wispy caprine beard dangling below a well-cragged face. He was likewise goatish in his implacable determination to keep going through mud and cold and scraped shins, with little patience for those who couldn't keep up."
— Clay Risen, The New York Times, 18 Dec. 2022

The public will often reach the same calculus, coming to see their attacker as an implacable threat that can only be neutralized through defeat.
—Max Fisher, New York Times, 11 Oct. 2022

Did You Know?
Implacable is rooted in Latin placare, meaning "to soothe," but its im- prefix is a variant of the negating prefix in- (as in inactive) and it signals that there’s nothing warm and fuzzy here.
Someone or something described as implacable cannot be soothed, which usually means trouble: implacable is most often attached to words like foe, enemy, hatred and hostility.
The opposite of implacable is, of course, placable; it means "easily soothed," but sadly isn’t called upon very often.
Another placare word is likely more familiar.
Placate means "to soothe or appease"; it’s frequently applied when an angry person is made to feel less so.