Definitions of glassy:

• adjective:   resembling glass in smoothness and shininess and slickness

  Example: "The glassy surface of the lake"

• adjective:   used of eyes lacking liveliness

  Example: "A glassy stare"

• adjective:   (of ceramics) having the surface made shiny and nonporous by fusing a vitreous solution to it

  Example: "Glassy porcelain"