The diagram illustrates the 'complexity' of the cell's structure.
He doesn't grasp/understand the 'complexity' of the situation.
Her poetry is too 'complex' [='complicated'] for my taste.
(..) As deep as lay the workers' city below the earth, so high above it towered the complex named the "Club of the Sons," with its lecture halls and libraries, its theaters and stadiums. Fathers, for whom every revolution of a machine wheel meant gold, had created for their sons the miracle of the (..)1927 Metropolis