Question: Why is a water glass called a tumbler?
Answer: According to the diligent students at Carlmont High School in Palo Alto, California, a tumbler is any drinking glass or cup that has no handles or stem. In the 17th century, it was a cup with a rounded or pointed bottom. If you set it down without draining the contents, it would tumble over and spill your beverage. The word itself comes from tumble, first recorded in English in the early 14th century, from the Germanic word for acrobat.