Meaning:

Be shaking your body a lot because you are cold, nervous, or frightened

If you are shaking like a leaf, you are shaking a lot especially when you are very cold, nervous or frightened.

Example: The child was shaking like a leaf while he was meeting with the principal.

I went to a place in the city, and I didn't know it was one of the most dangerous areas there. After I heard 5 people were shot and killed on the same day in the same place, I was shaking like a leaf.

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