Doubtful
Doubtful adjective - Not feeling sure about the truth, wisdom, or trustworthiness of someone or something.
Highly unlikely and doubtful are semantically related. In some cases you can use "Highly unlikely" instead an adjective "Doubtful".
Highly unlikely
Doubtful and highly unlikely are semantically related. Sometimes you can use "Doubtful" instead an adjective phrase "Highly unlikely".
Mutual synonyms
Both terms in one sentence
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However it is highly unlikely this applies to this class as even with how pompous Radisson is, it is doubtful that he had Josh take up half of his class every day.
Source: Film / God's Not Dead
Cite this Source
Highly unlikely and Doubtful. (2016). Retrieved 2026, August 09, from https://thesaurus.plus/related/doubtful/highly_unlikely
Doubtful & Highly unlikely. N.p., 2016. Web. 09 Aug. 2026. <https://thesaurus.plus/related/doubtful/highly_unlikely>.
Highly unlikely or Doubtful. 2016. Accessed August 09, 2026. https://thesaurus.plus/related/doubtful/highly_unlikely.
Google Ngram Viewer shows how "doubtful" and "highly unlikely" have occurred on timeline