Formidable and Hellacious

Formidable

Formidable adjective - Requiring considerable physical or mental effort.
Usage example: running a marathon is a formidable undertaking

Hellacious and formidable are semantically related. In some cases you can use "Hellacious" instead an adjective "Formidable".

Nearby Word: formidably

Hellacious

Hellacious adjective - Requiring considerable physical or mental effort.
Usage example: the pioneers survived a particularly hellacious river crossing with their covered wagon barely in one piece

Formidable and hellacious are semantically related. Sometimes you can use "Formidable" instead an adjective "Hellacious".
Cite this Source
Hellacious and Formidable. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/formidable/hellacious
Formidable & Hellacious. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/formidable/hellacious>.
Hellacious or Formidable. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/formidable/hellacious.
Google Ngram Viewer shows how "formidable" and "hellacious" have occurred on timeline