One to Many Relationship: Describing the Tables
The typical nomenclature for this type of table design would be "class-subclass".  In your example of Books and Authors, Books is a subclass of the Author class.  Any book automatically has an author, since no book can ever be written without having an author write it.  Same goes for Sales and SalesItems; each SalesItem must have an associated Sales object.

However, "parent-child" may be employed where it makes sense.  As is so often typical, the answer is It Depends™.

Using nomenclature that makes sense for the specific domain in question, and is easily and readily understood by the stakeholders, ensures future comprehension. 

One-to-many is a typical term used to describe the relationship between rows in each table.  The relationship might also be one-to-one or many-to-one or even many-to-many, depending on domain requirements.