Home›Browse›F›fiendishfiendishOur editors are putting together more complete content — check back in about 20 minutesfiendishfiendish — adjectiveadjective1. extremely cruel or unpleasant1.adjectiveDefinitionextremely cruel or unpleasantExampleHe devised a fiendish plan to torture his prisoners.2. very clever and difficult, often in a bad way2.adjectiveDefinitionvery clever and difficult, often in a bad wayExampleThe puzzle was fiendish, taking hours to solve.