A tumbler is a flat-bottomed beverage container usually made of plastic or glass. Theories vary as to the etymology of the word tumbler. One such theory is that the glasses originally had a pointed or convex base and could not be set down without spilling.A tumbler is a flat-bottomed beverage container usually made of plastic or glass. Theories vary as to the etymology of the word tumbler. One such theory is that the glasses originally had a pointed or convex base and could not be set down without spilling.A tumbler is a flat-bottomed beverage container usually made of plastic or glass. Theories vary as to the etymology of the word tumbler. One such theory is that the glasses originally had a pointed or convex base and could not be set down without spilling.A tumbler is a flat-bottomed beverage container usually made of plastic or glass. Theories vary as to the etymology of the word tumbler. One such theory is that the glasses originally had a pointed or convex base and could not be set down without spilling.A tumbler is a flat-bottomed beverage container usually made of plastic or glass. Theories vary as to the etymology of the word tumbler. One such theory is that the glasses originally had a pointed or convex base and could not be set down without spilling.A tumbler is a flat-bottomed beverage container usually made of plastic or glass. Theories vary as to the etymology of the word tumbler. One such theory is that the glasses originally had a pointed or convex base and could not be set down without spilling.A tumbler is a flat-bottomed beverage container usually made of plastic or glass. Theories vary as to the etymology of the word tumbler. One such theory is that the glasses originally had a pointed or convex base and could not be set down without spilling.A tumbler is a flat-bottomed beverage container usually made of plastic or glass. Theories vary as to the etymology of the word tumbler. One such theory is that the glasses originally had a pointed or convex base and could not be set down without spilling.A tumbler is a flat-bottomed beverage container usually made of plastic or glass. Theories vary as to the etymology of the word tumbler. One such theory is that the glasses originally had a pointed or convex base and could not be set down without spilling.