strenuous
adj. B2 Upper Intermediate US //ˈstɹɛnjuəs// UK //stɹˈɛnjuːəs// stren·u·ous
adj. needing a lot of physical or mental effort. You use this to describe tasks that are very tiring or difficult.
adj. requiring or using great exertion or high intensity. Often describes physical activities or mental efforts that test the limits of one's stamina.
The doctor told him to avoid strenuous exercise for a week.
After a strenuous day of hiking up the mountain, the group was exhausted but happy.
The legal team made a strenuous effort to overturn the verdict, citing several procedural errors that occurred during the initial trial.
From Latin strenuus (“quick”).
Usage
Commonly modifies nouns like 'exercise', 'effort', 'activity', or 'objection'.