implacable

Meaning

Adjective

• Not able to be placated or appeased.
• Impossible to prevent or stop; inexorable, unrelenting, unstoppable.
• Adamant; immovable.

Origin

• 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 (from plācō + -bilis).