insidious
UK[ɪnˈsɪd.i.əs]US[ɪnˈsɪd.i.əs]
adj
proceeding in a gradual, subtle way, but with very harmful effects.
adj
intending to entrap or beguile; treacherous.
Morpheme Breakdown
in
sid
ious
in
in
sid
sit
ious
adjective suffix
Etymology
the word insidious originates from the latin 'insidiosus', meaning 'cunning, deceitful, treacherous', which itself derives from 'insidiae', meaning 'an ambush, plot, or snare'. the literal meaning of 'insidiae' is 'a sitting in', from 'in-' (in) + 'sedere' (to sit), painting a vivid picture of an enemy lying in wait. this concrete image of a hidden, seated ambush evolved into the modern abstract sense of something that advances in a subtle, stealthy, and dangerously deceptive manner.
Analysis
Structure: in (in) + sid (sit) + ious (adjective suffix)
in (latin origin, meaning 'in, into, on'), sid (latin origin, from the root of 'sedere', meaning 'to sit'), ious (latin origin, adjective-forming suffix meaning 'full of, characterized by').
Examples
the disease is insidious, often showing no symptoms until it is too late for effective treatment.
he was the victim of an insidious plot to undermine his authority.
the film is a powerful critique of the insidious nature of corporate greed.