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"
engage or engross the interest or attention of beforehand or occupy urgently or obsessively; "His work preoccupies him"; "The matter preoccupies her completely--she cannot think of anything else"
occupy or take possession of beforehand or before another or appropriate for use in advance; "the army preoccupied the hills"