Heard of aglet (thanks Phineas and Ferb), grawlix (which I'm pretty sure was something Mort Walker just made up one day), tittle, defenestrate, bruxism, lemniscate, vaguely recognize obelus, and though "preantepenultimate" is new to me, I already recognized the "antepenultimate" part so I was able to easily deduce what it meant.