noun. Defined as an American who either works at the Renaissance Festival or attends the Renaissance festival. If a man, he is out of shape and has long hair and a beard and makes Simpsons and Monty Python references constantly. If a woman, she has a muffin top and wears clothing that doesn't fit and does not shave her pits. Ren Festers also have a penchant for speaking in phony British accents while drinking Mead and Cider Beer. They also enjoy traditional Celtic music and dress, such as Druid capes and kilts. Ren Festers also like fantasy novels and play a lot of Dungeons and Dragons.
Look at that guy in cape drinking Mead! He must be a total ren fester.
She is a total ren-fester.