implacable

adjective

im·​pla·​ca·​ble (ˌ)im-ˈpla-kə-bəl  -ˈplā- 

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

an implacable enemy

implacability

(ˌ)im-ˌpla-kə-ˈbi-lə-tē 

-ˌplā-

noun

implacably

(ˌ)im-ˈpla-kə-blē 

-ˈplā-

adverb

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.

Synonyms

• adamant
• adamantine
• bullheaded
• dogged
• hard
• hard-nosed
• hardened
• hardheaded
• headstrong
• immovable
• inconvincible
• inflexible
• intransigent
• mulish
• obdurate
• obstinate
• opinionated
• ossified
• pat
• pertinacious
• perverse
• pigheaded
• self-opinionated
• self-willed
• stiff-necked
• stubborn
• unbending
• uncompromising
• unrelenting
• unyielding
• willful
• wilful

Examples of implacable in a Sentence

He has an implacable hatred for his political opponents.

an implacable judge who knew in his bones that the cover-up extended to the highest levels of government

Recent Examples on the Web

The lesson drawn and instilled by his family was that the Gentile zeal for Jewish death is implacable and that only Jewish strength in a Jewish land can oppose it. —David Bezmozgis, New Yorker, 6 Apr. 2025

By casting Statham as a reluctant avatar of righteousness in a country that continues to prey on its own, and trusting that his implacable sense of honor will resonate with an audience who feel like they’ve been taken advantage of for their decency. —David Ehrlich, IndieWire, 26 Mar. 2025

The scale and brutality of the October 7 Hamas attack shook Israel and raised questions about its military competence and ability to defend itself against implacable enemies. —Elliott Abrams, Foreign Affairs, 17 Apr. 2024

In the great-power-competition narrative, those countries were positioned as implacable enemies, ideologically opposed to the U.S.-led order. —Stacie E. Goddard, Foreign Affairs, 22 Apr. 2025

Word History

Etymology

Middle English, from Latin implacabilis, from in- + placabilis placable

First Known Use

15th century, in the meaning defined above

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Kids Definition

implacable

adjective

im·​pla·​ca·​ble (ˈ)im-ˈplak-ə-bəl  -ˈplā-kə- 

: not possible to please, satisfy, or change

an implacable enemy

implacability

-ˌplak-ə-ˈbil-ət-ē 

-ˌplā-kə-

noun

implacably

-ˈplak-ə-blē 

-ˈplā-kə-

adverb