requiring more than usually expected or thought due; especially great patience and effort and skill; "found the job very demanding"; "a baby can be so demanding"
culpably involved; "all those concerned in the bribery case have been identified"; "named three officials implicated in the plot"; "an innocent person implicated by circumstances in a crime"
inspiring fear; "the formidable prospect of major surgery"; "a tougher and more redoubtable adversary than the heel-clicking, jackbooted fanatic"- G.H.Johnston; "something unnerving and prisonlike about high grey wall"
extremely impressive in strength or excellence; "a formidable opponent"; "the challenge was formidable"; "had a formidable array of compositions to his credit"; "the formidable army of brains at the Prime Minister's disposal"
not easy; requiring great physical or mental effort to accomplish or comprehend or endure; "a difficult task"; "nesting places on the cliffs are difficult of access"; "difficult times"; "a difficult child"; "found himself in a difficult situation"; "why is it so hard for you to keep a secret?"
requiring much effort and trouble; "the mountain climb was long, steep, and difficult"