This is my collection of long-term monitoring and development of Wiktionary material.
2004, Eric Blair, The Age of Unenlightenment: Mapping the Evolution and Adaptation of Enlightened Thinking, and Its Wreckage, Unauthorized Books, →ISBN, pages 173 pp.:
2007 August 19 (last accessed) “unenlightenment”, in Roget's New Millennium Thesaurus, First Edition (v 1.3.1), Lexico Publishing Group:
- earlier references in Hindu and Chinese philosophy, but not with the same connotation