UNSUBSTANTIATED Synonyms: 92 Similar and Opposite Words

unsubstantiated

adjective

ˌən-səb-ˈstan(t)-shē-ˌā-təd

Definition of unsubstantiated

as in unreasonable

having no basis in reason or fact an unsubstantiated claim that was thrown out of court

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Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

Recent Examples of unsubstantiated On Facebook, TikTok and Instagram, unsubstantiated claims often go unchecked. — Duaa Eldeib, ProPublica, 12 June 2026 The company alleged Fox broadcasted unsubstantiated allegations that Dominion's software manipulated vote counts, and the news organization settled for $787 million. — Aki Nace, CBS News, 24 June 2026 The resolution’s author, Assemblymember Marc Berman, D-Menlo Park, also connected it to a string of unsubstantiated accusations Trump has made in the last week about California ballot counting. — Stephen Hobbs, Sacbee.com, 10 June 2026 For the past several months, Owens has waged a digital terror campaign against Erika Kirk, spreading conspiracy theories about her husband’s death (and appearing to imply that Erika was involved in covering it up, an unsubstantiated narrative that somehow also involves Israel and Tucker Carlson). — Elaine Godfrey, The Atlantic, 9 June 2026 See All Example Sentences for unsubstantiated

Recent Examples of Synonyms for unsubstantiated

Adjective

His certification is temporarily suspended due to excessive or unreasonable force from the incident, according to the California Commission on Peace Officer Standards and Training.

— Theresa Clift, Sacbee.com, 7 July 2026
Your request for back-to-back weeks off at the last minute is unreasonable.

— Harriette Cole, Mercury News, 3 July 2026

Definition of unreasonable

Adjective

For decades, African football has faced criticism and skepticism, often based on unfounded racial stereotypes.

— PJ Green, Kansas City Star, 2 July 2026
The early fears that Hamilton was an existential threat to the university seemed—so far, at least—unfounded.

— Ann Manov, Harpers Magazine, 30 June 2026

Definition of unfounded

Adjective

Now, one population, transgender youth and collegians, are targeted for specific and baseless discrimination.

— Jackson Thompson OutKick, FOXNews.com, 30 June 2026
On the evening of June 2, his baseless case was further undercut when Republican Steve Hilton won the second spot on November’s ballot for governor, up against Democrat Xavier Becerra.

— Jackie Calmes, Mercury News, 19 June 2026

Definition of baseless

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unsubstantiality

unsubstantiated

unsubtle

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“Unsubstantiated.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/unsubstantiated. Accessed 8 Jul. 2026.

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Synonyms of unsubstantiated

adjective

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