Refers to the person who selects, compiles, or edits content for a publication, anthology, or dictionary. Not a general word for 'author' of original creative works.
The compiler of this dictionary is a renowned linguist.
Every piece selected by the anthology's editor is interesting.
Compound of 撰 (sen, 'select') and 者 (sha, 'person'). The kanji 撰 conveys choosing or compiling, reflecting the role of selecting content for a publication.