A fat that has one double bond between carbon atoms is called a monounsaturated fat.

Here's why:

* Unsaturated fats: These fats have at least one double bond between carbon atoms in their fatty acid chains.

* Monounsaturated: This term specifically refers to fats with only one double bond.

Some common examples of monounsaturated fats include:

* Oleic acid: Found in olive oil, avocados, and nuts.

* Palmitoleic acid: Found in some vegetable oils and seafood.

Monounsaturated fats are generally considered to be heart-healthy, as they can help lower bad cholesterol (LDL) levels and increase good cholesterol (HDL) levels.