Grueling (adjective)

1. Extremely difficult and tiring.
2. Extremely harsh or severe.

Origin:

From the verb "grue" (to shiver, shudder or feel a chill) in the late 16th century.

Examples:

1. The marathon was grueling and left the runners exhausted.
2. The hike up the mountain was grueling and took several days.
3. The job interview was grueling, with several rounds of questioning.
4. The soldier's basic training was grueling and lasted several weeks.
5. The math exam was grueling and left the students feeling drained.