An eponym is a word that was once a person's name but has come to have a broader meaning. Most eponyms are obvious — even if you don't know anything about the eponymous individuals, it's still clear that phrases like Benedict Arnold or Ponzi scheme or Achilles' tendon reference individuals (whether real or fictitious).
These proper eponyms don't interest me very much. I do enjoy, however, eponyms where the person's name has become such an utterly common word or phrase that the users of that word or phrase are completely unaware that it was formerly a person's name. I suppose the most typical examples of this kind of common eponym are sandwich (from the Earl of Sandwich) or teddy bear (from Teddy Roosevelt).
In the cumbersome paragraph below, each linked word is an eponym of this common sort:
Somehow, the diesel derrick's silhouette reminded the sideburn-wearing chauvinist of the daguerreotype of a mausoleum he had seen back when he was a mere guppy. "Bloomers or leotards?" his mentor asked. "Neither," the guy said. "I'm boycotting them. I'd rather be pierced by shrapnel, guillotined and lynched than to end up looking like a doily."Link: Wikipedia List of Eponyms