arduous

/ˈɑːdjuːəs/adjective

Demanding great effort and stamina; exhausting to carry out.

Example sentence

“The climbers faced an arduous trek up the mountain.”

Collocates with journey, task, climb, and process. Stronger than "difficult": it emphasizes the stamina required, not the complexity.

Related words

arithmeticThe branch of mathematics that deals with numbers and the basic operations of adding, subtracting, multiplying, and dividing.ardorIntense warmth of emotion; burning passion or enthusiasm.arrivalThe act of reaching a place, especially at the end of a journey.ardentFeeling or showing intense enthusiasm or passion.arriveTo come to a place; to reach one's destination.archeryThe sport or skill of shooting arrows from a bow.