underlying work; original work
Legal/copyright term for the original work from which a derivative work (二次的著作物) is created. Used in contexts such as copyright law, licensing, and adaptation rights.
See also: 二次的著作物
To translate it, you need permission from the author of the original work.
The copyright of a derivative work arises separately from the copyright of the underlying work.
二次的著作物 is a derivative work based on the 原著作物 (original/underlying work).
Compound of 原 (original) + 著作物 (copyrighted work). A straightforward legal term.