Other forms: pedantries
You know that person who is always interrupting other people, correcting their grammar or their facts? That's pedantry, or inappropriately showing off your knowledge.
The noun pedantry refers to the behavior of a pedant, which comes from the French word pédant, meaning “schoolmaster.” While it is a schoolmaster's job to ensure that students learn, someone who is guilty of pedantry just seems to brag, using his or her knowledge to get attention or seem better educated than the people around him or her.