Arduous
Arduous adjective - Requiring considerable physical or mental effort.
Usage example: climbing Mount Everest is an arduous, exhausting challenge
Formidable is a synonym for arduous in difficult topic. In some cases you can use "Formidable" instead an adjective "Arduous", when it comes to topics like demanding, heavy. popular alternative
Nearby Word: arduously
Formidable
Formidable adjective - Requiring considerable physical or mental effort.
Usage example: running a marathon is a formidable undertaking
Arduous is a synonym for formidable in difficult topic. You can use "Arduous" instead an adjective "Formidable", if it concerns topics such as heavy, onerous. popular alternative
Nearby Word: formidably
Mutual synonyms
Related pairs
Cite this Source
Formidable and Arduous. (2016). Retrieved 2026, August 15, from https://thesaurus.plus/related/arduous/formidable
Arduous & Formidable. N.p., 2016. Web. 15 Aug. 2026. <https://thesaurus.plus/related/arduous/formidable>.
Formidable or Arduous. 2016. Accessed August 15, 2026. https://thesaurus.plus/related/arduous/formidable.
Google Ngram Viewer shows how "arduous" and "formidable" have occurred on timeline