pernicious
UK: pəˈnɪʃəs | US: pərˈnɪʃəs
adj. extremely harmful or destructive, often in a subtle or gradual way
adj. (archaic) fatal; deadly
The word "pernicious" originates from Latin perniciosus, meaning "destructive" or "deadly," which itself comes from pernicies (ruin, destruction). The root nex (death) evolved into nic- in compounds, combined with the intensifying prefix per- to emphasize thorough harm. Over time, the meaning softened slightly to describe subtle but severe harm, retaining its negative connotation.
The pernicious effects of smoking often go unnoticed until serious health issues arise.
Propaganda can have a pernicious influence on public opinion.
The chemical spill caused pernicious damage to the local ecosystem.
His pernicious habits eventually led to his downfall.
The cult leader spread pernicious ideas that manipulated his followers.