insidious

UK: ɪnˈsɪd.i.əs | US: ɪnˈsɪd.i.əs

Definition
  1. adj. proceeding in a gradual, subtle way, but with harmful effects

  2. adj. intended to entrap or deceive; treacherous

Structure
in <in/into>sid <sit>ious <adjective suffix>
Etymology

insidious = in<in/into> + sid<sit> + ious<adjective suffix>

  • in (Latin origin, meaning "in" or "into")
  • sid (from Latin sidere, related to sedere, meaning "to sit")
  • ious (adjective-forming suffix indicating "having the quality of")

Etymology Origin:
The word insidious originates from Latin insidiosus ("deceitful, cunning"), derived from insidiae ("ambush, plot"). The root sid (from sedere, "to sit") metaphorically implies lying in wait, like a hidden trap. Over time, it evolved to describe actions or influences that operate stealthily, often with harmful intent.

Examples
  1. The disease has an insidious onset, with symptoms appearing only after significant damage.

  2. His insidious flattery masked his true intentions.

  3. The cult used insidious tactics to manipulate vulnerable individuals.

  4. Corruption spread through insidious means, undermining the system unnoticed.

  5. The software contained insidious malware that stole data silently.