Herculean

 
Pronunciation: /ˌhəːkjʊˈliːən, həːˈkjuːlɪən/

adjective

  • requiring great strength or effort: a Herculean task
  • (of a person) muscular and strong: the mesomorph, a classic Herculean build

Origin:

late 16th century (in the sense 'relating to Hercules'): from Latin Herculeus 'Hercules' + -an