Definition of "implacable" [im•pla•ca•ble]

• Impossible to placate or appease: implacable foes; implacable suspicion. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "So implacable is his revenge that he sends a party of soldiers into Egypt, some hundreds of miles, and they bring him back by force of arms."
• "Allegra’s tone was neutral, her expression implacable."
• "“Well, that’s as may be, Lady Nell, but it’s not right,” Linton declared, her arms folded, her expression implacable."
• "“Well, that’s as may be, Lady Nell, but it’s not right,” Linton declared, her arms folded, her expression implacable."
• "Rue Murillo, or in the tent at Croisset; he has recalled the implacable didactics of his old master, his tender brutality, the paternal advice of his generous and candid heart."
• "The doctrine is optimistic; and whoever has a generous faith in humanity will have no fault to find with the absence of the idea of implacable evil from its teaching."