Standard Lemma guide

treasonous

adj · 2 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

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  • CMU ARPABET: T R IY1 Z AH0 N AH2 S Digits mark lexical stress: 1 primary, 2 secondary, 0 unstressed.

1

adj

Meaning 1

Like or in the way of treason.

Definition source: English Wiktionary via Wiktextract

Usage: not-comparable

Examples

  • His treasonous actions earned Benedict Arnold eternal scorn.

Meaning relationships

Synonyms: dastardly, perfidious, traitorous, booky, disleal, disloyal, double-crossing, double-dealing, double-faced, double-hearted, doublehearted, faithless, false, falseheart, false-hearted, guiled, guileful, hollow-hearted, illoyal, infidelitous, insidious, Judaslike, Judasly, nonfaithful, proditorious, proditory, Punic, ratlike, recreant, renegade, reptilian, reptitious, swike, traitorish, traitorlike, traitorly, traitorsome, treacherous, treachersome, trothless, unfaithful, unleal, unloyal, unsteadfast, untrue, viperish, viperous

Antonyms: none provided

2

adjective satellite

Meaning 2

having the character of, or characteristic of, a traitor

Definition source: Princeton WordNet 3.0

Examples

  • the faithless Benedict Arnold
  • a lying traitorous insurrectionist

Meaning relationships

Synonyms: faithless, traitorous, unfaithful, treasonable

Antonyms: none provided

History

Etymology

Etymology tree English treason Proto-Indo-European *h3ed- Proto-Indo-European *-os Proto-Indo-European *h3édosder.? Proto-Italic *-ŏ̄dsos? Old Latin -ōssus Latin -ōsus Old French -usbor. Middle English -ous English -ous English treasonous From treason + -ous.