Vocabulary Building: “INSIDIOUS” – Meaning and Usage

In today’s video we’ll continue to expand our vocabulary and learn a new English word – “insidious.”

Let’s break it into parts and learn the word’s origin.

The root of the word – “sid” comes from Latin “sedere,” which means “to sit.”

Prefix “in-” also comes from Latin and means “in” or “inside.”

These words together, by the way, form the word “insidia,” which in Latin means “ambush.”

And suffix “-ous” in English helps form an adjective.

Thus, the literal meaning of “insidious” is “sitting in an ambush.”

To be insidious means to progress gradually but with inevitable harm. Or, having “hidden harm,” as if sitting in an ambush.

Here is an example of how to use the word in a sentence:

“Many diseases are insidious because they progress without dramatic symptoms before disabling the victim.”

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Tutor Phil

Tutor Phil is an e-learning professional who helps adult learners finish their degrees by teaching them academic writing skills.

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