Here’s another muscular word from my Arsenal for the Articulate:
What it Means: Describing something that moves in a gradual way but is ultimately very damaging. Sometimes the meaning is broadened to something that is stealthily intended to entrap, such as a carefully planned and slow-moving plot.
How to Use It: “High blood pressure is the most insidious of disorders because it generally presents no symptoms until a devastating stroke.”
About the Word: It’s from the Latin word for “sit,” which is either “sid” or “sed” depending on the way it is used in a Latin sentence. Sid/sed unlocks many English meanings, including “sedentary” (sitting a lot), “sedative” (a drug that makes you sit or lie down), and “assiduous,” meaning, literally, being so thorough that you “sit down with your work.” “Insidious” came from the practice of Roman soldiers who would sit low to the ground and wait in hiding to ambush opposing troops. (Now that you know the story, try to forget the word. I challenge you.)