What is a synonym for the word grueling?

Here are some synonyms for "grueling," depending on the specific context:

General synonyms:

* Exhausting

* Strenuous

* Arduous

* Rigorous

* Demanding

* Difficult

* Tough

* Tiring

* Laborious

More intense synonyms:

* Backbreaking

* Herculean

* Intense

* Unrelenting

* Brutal

Synonyms focusing on mental strain:

* Stressful

* Taxing

* Trying

The best synonym will depend on the specific context of your writing.