What is a piece of dough saved from another batch called?

A piece of dough saved from another batch is called a starter or a mother dough.

* Starter is a common term for a leavened dough used to initiate fermentation in another dough.

* Mother dough is a more specific term for a sourdough starter, which is a mixture of flour and water that is fermented by wild yeast and bacteria.

Both terms can be used interchangeably, but mother dough is more precise when referring to sourdough.