Fastness and Perfidiousness
Opposite meaning words
Fastness
Fastness noun - Adherence to something to which one is bound by a pledge or duty.
Usage example: his uncompromising fastness to the cause of freedom was beyond question
Perfidiousness is an antonym for fastness.
Nearby Word: fasten
Perfidiousness
Perfidiousness noun - Lack of faithfulness especially to one's husband or wife.
Fastness is an antonym for perfidiousness.
Cite this Source
Perfidiousness and Fastness. (2016). Retrieved 2026, August 13, from https://thesaurus.plus/related/fastness/perfidiousness
Fastness & Perfidiousness. N.p., 2016. Web. 13 Aug. 2026. <https://thesaurus.plus/related/fastness/perfidiousness>.
Perfidiousness or Fastness. 2016. Accessed August 13, 2026. https://thesaurus.plus/related/fastness/perfidiousness.
Google Ngram Viewer shows how "fastness" and "perfidiousness" have occurred on timeline