Formidable
Formidable adjective - Requiring considerable physical or mental effort.
Usage example: running a marathon is a formidable undertaking
Tough is a synonym for formidable in demanding topic. In some cases you can use "Tough" instead an adjective "Formidable", when it comes to topics like difficult, heavy.
Nearby Word: formidably
Tough
Tough adjective - Requiring considerable physical or mental effort.
Usage example: even if you study for it, it's still a tough exam
Formidable is a synonym for tough in heavy topic. You can use "Formidable" instead an adjective "Tough", if it concerns topics such as arduous.
Mutual synonyms
Both words in one sentence
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Despite having the near-useless power to breathe underwater, he's one tough mother, and probably the most formidable and successful crime-fighter on the team.
- Hmmm... Puny Earthling: The witches are astonished at how frail Earth creatures are; even without their magic, witches are extremely tough and physically formidable creatures, and their Death World homeworld is likewise filled with animals that have evolved to be much stronger than Earth animals.
Cite this Source
Tough and Formidable. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/formidable/tough
Formidable & Tough. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/formidable/tough>.
Tough or Formidable. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/formidable/tough.
Google Ngram Viewer shows how "formidable" and "tough" have occurred on timeline