A snifter is a short-stemmed glass with a wide bottom and a narrow top that is most often used to serve?

If you are referring to the drinking glass also known as a brandy snifter, this is a short-stemmed glass (a wine glass is long-stemmed) with a wide bowl but narrow top, kind of like a teardrop with the point cut off. This shape temporarily traps the aromas in the glass, allowing the drinker to sniff the brandy, cognac, or Kool-Aid. Hence, the name "snifter."