1. Someone who disagrees with an assertion in a controversial political debate: Judy turned out to be a denialist in the local government when she opposed the statement made by the chairman to be unsatisfactory and incorrect concerning the kindergarten that was to be built.
2. Anyone who has increasingly come to maintain personal beliefs even in the face of solid scientific evidence: A denialist refers to a person who opposes a range of issues from childhood vaccines to genetically modified foods, maintaining that living in a totally natural and healthier way is better.