A system of writing using wedge-shaped marks impressed into clay tablets.
Here's why:
* Cuneiform is a script: It's a system for representing language in written form.
* Wedge-shaped marks: The distinctive feature of cuneiform is the use of wedge-shaped marks made by pressing a stylus into soft clay.
* Clay tablets: The most common material for cuneiform writing was clay tablets, which were baked to preserve the writing.
So, while cuneiform is an ancient form of writing, its defining characteristic is the use of wedge-shaped marks impressed into clay.