A more thorough explanation:

Definition: A foreign substance is a substance that is found in a body, organism, or thing where it is not supposed to be found. For example, if you find a piece of glass in your hamburger, that is a foreign substance.

Example: The plaintiff sued the restaurant because she found a foreign substance (a piece of glass) in her hamburger.

Explanation: The example illustrates the definition of a foreign substance because the piece of glass was not supposed to be in the hamburger. It was a foreign substance that could have caused harm to the person who ate it.

Additional Example: If you find a hair in your food, that is also a foreign substance because it is not supposed to be there.

Explanation: This example shows that a foreign substance can be any substance that is not supposed to be in a particular place. In this case, the hair is not supposed to be in the food, and it could be harmful if ingested.