adjective

arduous

AR-joo-uhs/ˈɑːrdʒuəs/

Requiring great effort and causing tiredness.

The exhausted backpacker faces an arduous climb up the rocky trail.

A visibly exhausted backpacker struggles up a steep, rocky trail, leaning heavily on a trekking pole while hauling herself onto a high natural step.

Etymology

Latin arduus meant “high” or “steep,” and figuratively “difficult” or “hard to reach.” An arduous task carries the image of a steep climb, demanding sustained effort.

In context

Free Documentary35:34

would be an arduous task. Five people have to work 10 hours straight loading eight of these steel cylinders onto the ship.

World's Longest Cross Sea Bridge | China's Mega Projects | Free Documentary

More examples

Moving the piano upstairs proved arduous, even with four people helping.
Recovering from the injury is a slow, arduous process.
The team spent an arduous week checking thousands of records.

Forms

arduous

arduously adverb — With great effort and difficulty.

arduousness noun — The quality of requiring tiring effort.

Similar words

strenuous: Emphasizes vigorous exertion, especially physical effort, rather than difficulty.
grueling: Suggests especially severe effort that leaves someone exhausted.
demanding: Requires considerable effort or attention without necessarily causing exhaustion.