Parent rock is a term used in geology to describe the original rock from which a secondary rock is formed. These secondary rocks can be created through processes such as weathering, erosion, and metamorphism. Synonyms for parent rock include source rock, protolith, and precursor rock. In sedimentary rocks, the parent rock is often referred to as the sediment source or sediment donor. In metamorphic rocks, the parent rock is called the protolith, indicating that it was the precursor to the new rock. Understanding the parent rock of a secondary rock is important in studying geological formations and in determining their history and evolution over time.