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Definition of treasonous

treasonous

/ˈtriːzənəs/
trea · son · ous
Adverb:treasonously
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treasonous Lexical Profile

treasonous Game Scores & Validity

• adjective

1

Involving, constituting, or guilty of the crime of betraying one's country or sovereign.

Example

"The historical tribunal examined letters that revealed a treasonous plot to overthrow the monarchy."

Synonyms
View all synonyms for treasonous
Antonyms
View all antonyms for treasonous

Word Nuance & Usage

While 'treasonous' and 'treasonable' are closely related, 'treasonable' is preferred in strict legal contexts to mean punishable as treason under the law, whereas 'treasonous' more broadly describes the nature, intent, or character of an act or person.

• Nearby Words

treason
treasonable
treasonably
treasonous
treasure
treasured
treasurer

Word Origin & Etymology

Formed in the late 16th century from 'treason'—which entered Middle English via Anglo-Norman 'treisoun' from Latin 'traditio' (a handing over or surrender)—combined with the suffix '-ous'.

Cite this Entry

Wordmom. (2026). Definition of Treasonous. In Wordmom Dictionary. Retrieved Nov 5, 2026, from https://wordmom.com/dictionary/treasonous
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