Heavily cratered regions are called lunar highlands or terrae, especially when referring to the Moon.

Here's why:

* Lunar Highlands: This is the most common term, referring to the elevated, heavily cratered areas of the Moon's surface. They are older than the smoother maria (darker regions) and have been bombarded by impacts for billions of years.

* Terrae: This term is used in a broader sense, referring to continental-scale areas of elevated, heavily cratered terrain on other planets and moons. For example, the "Terrae" on Mars.

The term "heavily cratered regions" itself is less specific but still accurately describes the characteristics of these areas.