Someone who demands an exceptionally or unreasonably high level of minute detail or accuracy in something. Used especially in reference to hobbyists, particularly in the field of model train building. I might be considered a rivet counter by others, but I'm particularly proud of the level of detail that goes into my model sets. I can't stand seeing movies with a rivet counter like Jerry. After every film, he just sits there listing all the factual inaccuracies in it rather than just enjoying the darn thing!