treacherous
UK: ˈtretʃərəs | US: ˈtretʃərəs
adj. 1. Guilty of or involving betrayal or deception.
adj. 2. Hazardous due to hidden or unpredictable dangers.
treacherous = treach<deceive> + erous<adjective suffix>
- treach: From Old French trechier ("to deceive"), derived from Vulgar Latin triccare ("to cheat"), related to Latin tricari ("to evade, play tricks").
- erous: An adjectival suffix indicating "full of" or "characterized by," akin to -ous in English (e.g., dangerous → dangerous).
Etymology Origin:
The word treacherous traces back to medieval notions of deceit, rooted in the Latin tricari ("to play tricks"). Over time, treach evolved in Old French to mean outright betrayal, while the suffix -erous solidified its adjectival form in English. The term originally described intentional deception (e.g., treason) but later expanded to describe natural hazards that "betray" trust, like unstable terrain.
The treacherous spy sold secrets to the enemy.
Mountain roads become treacherous during ice storms.
His treacherous actions cost him the trust of his allies.
The river’s currents are deceptively treacherous.
She navigated the treacherous politics of the corporate world with caution.