Insidious
Insidious adjective - Working or spreading in a hidden and usually injurious way.
Unfrank and insidious are semantically related In some cases you can use "Unfrank" instead an adjective "Insidious".
Nearby Word: insidiously
Unfrank
Mutual synonyms
Cite this Source
Unfrank and Insidious. (2016). Retrieved 2026, August 02, from https://thesaurus.plus/related/insidious/unfrank
Insidious & Unfrank. N.p., 2016. Web. 02 Aug. 2026. <https://thesaurus.plus/related/insidious/unfrank>.
Unfrank or Insidious. 2016. Accessed August 02, 2026. https://thesaurus.plus/related/insidious/unfrank.
Google Ngram Viewer shows how "insidious" and "unfrank" have occurred on timeline