Pepsin (noun)

1. An enzyme that helps to break down proteins in the stomach.
2. A digestive enzyme present in the stomach that breaks down proteins into smaller peptides, allowing for easier absorption by the body.

Origin:

From greek pepsis ("digestion"), means an enzyme that helps to break down proteins in the stomach.

Examples:

1. Pepsin is an enzyme that breaks down proteins in the stomach.
2. Pepsin works in an acidic environment.
3. Pepsin plays an important role in the digestion of proteins.
4. Pepsin is produced by the stomach.
5. Pepsin is activated by hydrochloric acid.