implacableunable to be appeased or satisfied; relentless and unyieldingThe implacable critic refused to soften her stance despite the director's personal appeal.NoteThe implacable critic refused to soften her stance despite the director's personal appeal.Elon.io is an online learning platformWe have an entire course teaching GRE Verbal — Essential Vocabulary grammar and vocabulary.Start learning GRE Verbal — Essential Vocabulary now