What is the meaning of arduous?

Difficult, strenuous, hard to accomplish or achieve.
1.
requiring great exertion; laborious; difficult: an arduous undertaking.
2.
requiring or using much energy and vigor; strenuous: making an arduous effort.
3.
hard to climb; steep: an arduous path up the hill.
4.
hard to endure; full of hardships; severe: an arduous winter.