implacable

Adjective

implacable (comparative more implacable, superlative most implacable)

1. Not able to be placated or appeased.
   • He is knight dubb'd with vnhatche'd Rapier, and on carpet conſideration, but he is a diuell in priuate brall, soules and bodies hath he diuorc'd three, and his incenſement at this moment is ſo implacable, that ſatisfaction can be none, but by pangs of death and ſepulcher: Hob, nob, is his word...c. 1601–1602 (date written), William Shakespeare, “Twelfe Night, or What You Will”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and...
   • [I]n the reign of Henry the Second, a body happening, by chance, to be dug up near Glastonbury Abbey, without any symptoms of putrefaction or decay, the Welch, the descendants of the Ancient Britons, tenacious of the dignity and reputation of that illustrious hero [King Arthur], vainly supposed it...1810, J[ohn] Stagg, “Arthur’s Cave. A Legendary Tale.”, in The Minstrel of the North: Or, Cumbrian Legends. […], London: Printed by Hamblin and Seyfang, […], for the author, and sold by J. Blacklock...

   Synonyms:

   impacable, irreconcilable, unassuageable, unplacable, unpleasable

   Antonyms:

   appeasable, assuageable, pacable, pacifiable, placable

2. Impossible to prevent or stop; inexorable, unrelenting, unstoppable.
   • The battleships Washington and South Dakota pushed through the sea with an implacable ease.2011, James D. Hornfischer, “The Giants Ride”, in Neptune’s Inferno: The U.S. Navy at Guadalcanal, New York, N.Y.: Bantam Books, →ISBN; trade paperback edition, New York, N.Y.: Bantam Books, 2012...

   Synonyms:

   relentless, unremitting, unyielding

3. Adamant; immovable.
   • Indeed Cain hated his Brother, becauſe his own works were evil, and his Brothers righteous; and if thy Wife and Children have been offended with thee for this, they thereby ſhew themſelves to be implacable to good; and thou haſt delivered thy ſoul from their blood.1678, John Bunyan, The Pilgrim’s Progress from This World, to That which is to Come: […], London: […] Nath[aniel] Ponder […], →OCLC; reprinted in The Pilgrim’s Progress (The Noel Douglas Replicas)...