noun
collected works; collection; collected edition
Refers to a published collection of an author's writings, such as a complete works or selected works. Often used in book titles.
漱石の著作集を全巻そろえた。
I collected all volumes of Soseki's collected works.
選集 is a selected works, often a curated subset, whereas 著作集 can be broader or more general.
Compound of 著作 (chosaku, 'writing, authorship') and 集 (shū, 'collection').